"Good day, boys!"
Translation:Bonan tagon, knaboj!
j is for plurals.
Boys = knaboj cats = katoj houses = domoj
n is the accusative. It's primarily to mark the object of a sentence so you know who is doing what to who within the context of Esperanto's flexible structure. For example, take the following sentence without the accusative:
La viro manĝis la kokaĵo. La kokaĵo manĝis la viro.
Both word orders are grammatically correct, so how do you tell who's being eaten? Common sense and context will generally clue you in, but grammar isn't concerned with how obvious the answer might be, so if you add it, you can have:
La viro manĝis la kokaĵon. La kokaĵon manĝis la viro.
Both of the above are valid and both tell you that the man ate the chicken, while the below...
La kokaĵo manĝis la viron. La viron manĝis la kokaĵo.
...mean that the chicken at the man, which is hilarious, but wrong. There's more to it than that, but that's a simple overview. You also apply suffixes to objects when they tie together, like "The cat attacked the blue dog" would be "La kato atakis la bluan hundon"
For further info, reading the notes on each Duolingo lesson as well as other resources like Lernu.net are helpful.
Just realized I missed that you said "jn" and not just "n". My bad. Suffixes can stack together. Taking the cat attacking the dog example and modifying it:
"The cats attacked the blue dogs."
would be written as
"La katoj atakis la bluajn hundojn"
Both "bluajn" and "hundojn" have three endings. Taking "hundojn" for example:
hund = dog -o = tells you it's a noun -j = tells you it's plural -n = tells you it's the object of an action.
Pretty much the same for "bluajn" except the -a denotes adjective since you're describing something.
Be sure to read the tips and notes (lightbulb icon), or do a grammar-based course like free-esperanto-course.net . .. and for a quick answer - see number 6 in this forum post.
Be sure to read the tips and notes (lightbulb icon), or do a grammar-based course like free-esperanto-course.net . .. and for a quick answer - see number this forum post.
Be sure to read the other comments and the tips and notes (lightbulb icon), or do a grammar-based course like free-esperanto-course.net . .. and for a quick answer - see number this forum post.