"I have a child."
Translation:У меня есть ребёнок.
«Я» is used for the grammatical subject of the sentence, while here "I" is not a grammatical subject.
Russian handles sentences about 'having' differently from English.
In English "I have a child", "I" is the grammatical subject, "I" does the action of 'having', and that action is directed at a child.
In Russian, we use a completely different way to say things: "By me, there is a child". We use a preposition "у" to indicate a possessor, and the 'child' is the grammatical subject who is doing the action of 'being', 'a child is'.
Well, probably? Language is redundant, so we can often guess the meaning of the sentence even if it's incorrect just because we have a context. But «я меня есть ребёнок» sounds like "I me a child".
The Russian sentence literally means something like 'By me, there-is a child'. It's not really 'by' («у» only means 'by, near' when it's used with non-living things), it's a preposition indicating possessor, but English doesn't have anything similar. If that helps, you can mentally translate у меня́ as 'at my possession', 'at my place', or, in this sentence, 'in my family'.
Есть is tricky. It's literally a present-tense verb 'to be', so it's translated '[there] is'. But it's omited unless it is a part of the new meaning told in the sentence:
- У меня́ есть ребёнок. The fact that I have a child is a part of the new information. It can be contrasted with "I don't have a child".
- У меня́ ребёнок. The fact that I have someone is assumed. The new information is that someone I have is a child. It can be contrasted with "I have my reasons", or with "I have a work to do". The fact that I have someone is assumed by the context.
The second option usually only works when there is a certain context. Since Duolingo presents sentences out-of-context, «У меня́ ребёнок» sounds less natural here. It might work in real-world texts, where there is more context.
Because де́ти is plural, and ребёнок is singular. Since the English sentence has a singular 'a child', you should use a singular noun in translation.
Де́ти is a suppletive form. It means it used to be a form a different noun in the past (дитя́), but came to be used as a plural of ребёнок. (Compare the English form 'went'. It used to be a form of the verb 'to wend', but came to be used as a past form of the verb 'to go'.)
In some sentences with "I have" the word есть is omitted (in more informal speech), but in most cases it must be. In this sentence you can say "У меня ребёнок."
«У меня» is "at my [possession/place]", «у тебя» is "at your [possession/place]". The former is a form of «я» 'I', the latter is a form of «ты» 'you' (informal singular form).
Sorry? There's no "p'esh" in this sentence (at least I can't see it).
I'm not familiar with a Latin transliteration used in Duolingo, but if I saw "p'esh" I'd think it's «пьёшь», i.e. '[you] drink'. However, this sentence doesn't have this word, so I'm not sure how it's related to this sentence and what you're exactly asking about.
Maybe you could reword your question?