Learn Turkish: O zaten çok genç. - He is very young anyway.

In Turkish, the "to be" verb for the third person (he/she/it) often doesn't use a suffix. While you could add a suffix to make it gençtir, in everyday speech, just saying O ... genç is perfectly complete and means "He is young".

Does o mean "he", "she", or "it"?

It can mean any of them! Turkish doesn't have gendered pronouns. You know whether o means "he", "she", or "it" strictly from the context of your conversation. Here, we translated it as "he", but "She is very young anyway" is equally correct.

I thought zaten meant "already". Why is it translated as "anyway" here?

Zaten is a versatile word. It often means "already", but it is also commonly used to mean "anyway", "besides", or "as a matter of fact". Native speakers use it a lot to emphasize that something is an established or obvious fact.

Could we put zaten at the end of the sentence, like we do with "anyway" in English?

It is much more natural to put zaten right after the subject (O). In Turkish, words that emphasize or modify the situation usually come before the main adjective or verb, rather than being tagged on at the very end of the sentence.