"What is her age?"
Translation:Onun yaşı kaç?
So She and He doesn't matter?
Right. Turkish doesn't distinguish grammatically between people who are male and people who are female.
The language considers it just as irrelevant as people who are left-handed and people who are right-handed, for which nobody has separate pronouns, either.
o can be "he" or "she" -- or any other pronoun a person might want. It refers to one person, without saying anything about their gender or handedness or nationality or skin colour.