As far as I know, it's simply a construction in Esperanto for saying that something exists.
In English, when you say "It is an important day", "it" doesn't really refer to anything specific, it just has to be there for the sentence to be complete. Similar with "There is/are" -- you're not literally referring to a specific location whenever you say that phrase.
In Esperanto, "Ĝi estas grava tago" would but an emphasis on ĝi, meaning that you're referring to a specific day which would be obvious if there was context. The sentence as it is, without ĝi, implies that today is an important day in the park.
Take it all with a grain of salt since I'm an Esperanto beginner as well, though.
The comment that you're referring to already has some good answers posted to it When translating "it is" you only use "gxi" if there's an actual "it" in the world doing the thing. The "it" in "it is an important day" is simply a grammatical placeholder in English and doesn't refer to an "actual it" -- so no "gxi".
What is "This" referring to? Do you accidentally click "Post" before you had finished?
There are a lot of non-native English speakers on these comments pages -- I expect them to NOT understand English this/that references. So I just repeat the subject, which also removes a lot of ambiguity, and makes my writing clearer in general. Repeating the subject for non-English speakers is something I learned when doing international tech support for a really complicated programming product. <-Note that the bolded section could have been a "this".
Also, on the Duolingo comments pages, likes and dislikes can move replies away from the original posting.
"There is an important day in the park" is now accepted - I just tried it!
Sometimes the course authors add clearly wrong answers (and by clearly wrong, I mean answers which nobody, even the course authors themselves, believes to be correct), with the goal of "not frustrating" learners. These include obvious misspellings such as "breath" for "breathe" -- and apparently "there is" when context clearly calls for "it is."
If someone were to say "Ni iru! Estas grava tago en la parko." There would be no doubt that he was talking about today. It's an important day in the park. Without the "ni iru" it would also be clear that it means "it is."
So the answer to zbrojny120's question is that when talking about things like days, with no contrived context, "it is" is the first meaning that should spring to mind, since, generally speaking, things like days aren't found lying around in parks.
It is true that "there is a day" is a possible translation, but only if there was a context that made that seem plausible. "Cxujare, estas grava tago en la parko." Yearly, there is an important day in the park. Without some special context, possible does not mean "likely" or "best."
In English, we use a before any word with a consonantal sound. An is used before vowels. There are exceptions to this, words which start with an h being the largest one.
Since you speak Spanish you should recognize the word naranja which came into English as "a noranj" and fairly quickly turned into "an orange." Esperanto fixes this "feature."
So I recently fixed my email notifications and now I'm seeing threads which I haven't seen in a year. I'm finding that a number of my comments have been stupidly downvoted with no better answer suggested. Looks like I'm not the only one. For the life of me I can't imagine why someone would downvote EM's comment. At times this sort of thing is almost funny.
Yeah, I've seen a lot of my comments downvoted, sometimes multiple times. Helpful, factual comments.
I've seen entire threads downvoted for no good reason. I think it's a matter of children and other immature people getting bored and just deciding to play downvote fairy.
I do think that's the case in at least a few of the situations. My perspective changed a lot when I found out that my youngest child had gone onto the duolingo board and I saw how people were reacting. I'm much more forgiving now. (And I hope others are forgiving of me.) Always assume positive intent.
I also think that people downvote answers they don't understand. Sometimes this is my fault, and sometimes the answer is really more complicated than people initially suppose. Occasionally people seem not to like it when I disagree with the course authors on a fine point. (Clearly they're thinking "who are YOU to disagree with the volunteers?)
People downvote clutter to move it out of the way of the useful grammar discussion and recommendations of resources. Three downvotes collapses a comment and its following thread (if any.)
Given how useful those grammar discussions are, and how much the popular courses get uselessly cluttered (see the comments sections in the earlier portion of the Spanish course, for instance) I think they have a point.
I agree that leaving a few "thank you's" around improves the atmosphere, though.
I've been on the board for two years, I think. I certainly see the value in downvoting clutter. People post "thank you" all the time and I don't see the point in voting this one down and not the others, but as Rae.F said, it's quite likely the "downvote fairly" going around.
I also think that people downvote answers they don't understand. It's better to ask question ... the big thing that was on my mind when I wrote my previous comment six months ago was that people were voting things down and not putting up a better answer. To me, that's pretty lame. It doesn't apply here - but this must have reminded me of it.
No, it's very different.
When Grandma says "eat", this is an imperative. This is well understood and works the same in English and Esperanto. In Esperanto you use a -u ending (manĝu!) and the assumption is that you give a command, you're giving it to the person you're talking to -- so saying "you eat!" would be redundant. In English it would also be mistaken for an indicative sentence meaning "I know that you eat on a regular basis."
However, with "It is an important day", the word "it" is just a grammatical placeholder. Just like in "it's raining". When we say that it is raining, there's no actual it doing the action. In these situations, we don't use a subject in Esperanto. "Pluvas" (it's raining). For this reason these are often called "weather verbs" -- although they're also called "impersonal".