"I have a sister."
Translation:У меня есть сестра.
It's a bit context dependent. When present, «есть» indicates the existence of something that may or may not be there. E.g., if your listeners are not yet aware whether or not you have any siblings, «есть» would be called for. You would omit it, however, if the topic of siblings is already being discussed and the goal is to simply state their gender (e.g., someone else has already mentioned having a brother).
In any case, both are grammatically correct, and you will never risk being misunderstood if you drop «есть».
They are not even close. Я is indeed "I" (nominative). У is a preposition similar to English "by". What confuses you is that the most typical way of saying "I have X" in Russian is "У меня есть X", which grammatically corresponds to something like "X is by me". So "By me" is "у меня" (dative - as required by preposition "у").
There is a subtle difference between the two. You should use "есть" when the existence of something is in question. E.g., if it's not known to the other party whether you have any siblings, "есть" is warranted. On the other hand, if it's expected that you have a sibling, and you simply state that it's a sister, not a brother, "есть" is not needed.
you wanted the other kind of answer
Are you addressing me? I merely explained the difference between the two, so perhaps a simple "thanks" would suffice?
If you feel your answer should be accepted - use the appropriate report option. I am not a contributor to this course, I did not come up with these examples and I cannot just add possible translations. And I most certainly do not want anything (including any kind of answers) from you. Please exercise your attitude elsewhere.
There's something a bit off with this task. First I entered 'u menja sestra' (which is very close to the suggested answer here, and as mentioned by other people here). However, Duolingo went off on a tangent... it of course said my answer is wrong, but it did NOT suggest that the 'est´' should be there. It said the right answer is 'Ja imeju sestru'! That's an entirely new construct to me, besides I couldn't possibly have known how those words are conjugated (they haven't appeared at all before this).
Could the developers please consider adding tiny bits of "pre-reading" or something? As it is now, many times it is 100% pure GUESSWORK to get the tasks right. In books, there are usually short sections explaining the aspects of the grammar that you can then logically use to actually think your way through the problem. Why not here?
If I had started Russian from scratch on Duolingo, I think would have hit the wall almost straight away... I've studied it elsewhere just a tiny bit and that helps SO MUCH. Too much in fact, that's why I feel like Duolingo needs improvement so much. It's more like a TEST of your abilities than a LEARNING tool (which is what it is supposed to be).
"U menya yest' sestra." is not accepted.
Is there a different transliteration I should be using? I tried several ways after that, but don't know ....nothing was accepted and I had to copy the Russian from google translate just to get past this item. Also, google translate put the transliteration how I had it too.
Any mods care to explain? Thanks.
I simply can't figure out how to input the soft sign with a US keyboard. Most of the other Cyrillic letters can be typed like in the official transliteration, but none of the usual apostrophes or accent marks work for the soft sign.
What does work is to put some random letter where the soft sign is, then it's accepted as a 'typo'. I usually use 'j'. But it would be more satisfying to get it really right.