This is the 671st most frequent Lithuanian word.
sostinės
The Lithuanian word "sostinės" means "capitals" (plural form of "capital city").
In this sentence, 'sostinės' is the possessive form of 'sostinė' (capital) indicating ownership or relation, meaning 'of the capital'.
Vilnius yra Lietuvos sostinės miestas.
Vilnius is the capital city of Lithuania.
Here, 'sostinės' is used in plural form to signify multiple capitals.
Knyga apie Europos sostinės yra labai įdomi.
The book about European capitals is very interesting.
In this sentence, 'sostinės' is used in genitive singular form to describe something pertaining to the capital.