This is the 868th most frequent Croatian word.
čija
"Čija" means "whose" in English.
In this descriptive sentence, 'čija' links the main noun 'knjiga' (feminine singular nominative) to an attribute clause that describes its ownership.
Ovo je knjiga čija je autorica poznata.
This is a book whose author is famous.
Here, 'čija' is used as a relative pronoun referring to the noun 'torbu' (feminine singular accusative), indicating possession in the clause.
Pronašla sam torbu čija je boja crvena.
I found a bag whose color is red.
In this interrogative sentence, 'čija' is used to ask about the ownership of the noun 'book' (feminine singular nominative).