"Whose daughter is it?"
Translation:Чия це донька?
It is an indicator, "це" can be translated as "this", without this word you can only use the sentence when the person was talking about family relations and you make a question to what you just heard, whether you didn't hear properly or ask in surprise.
- So that girl over there is my daughter.
- Чия донька? (Whose daughter?) Yours? I could never tell, you look like sisters!
But with "це" the sentence can be a conversation starter, you ask out of interest or other scenarios. Without "це" the usage is more narrow, more specific