"This is my younger sister."
Translation:Це моя молодша сестра.
Why do we say Це here? If "a" is the ending of a feminine word, wouldn't it be Ця?
ця (this) is a demonstrative pronoun. You would use it in combinations like this car, this girl, this weather (ця машина, ця дівчина, ця погода). It is different from This is a car. This is a girl (Це машина. Це дівчина)
That makes much more sense, thank you.