This is the 13th most frequent Serbian word.
која
"Која" means "which" or "that" (feminine singular form).
The word 'која' is used as a relative pronoun to introduce a relative clause that provides more information about the noun 'књига' (book).
Књига која лежи на столу је моја.
The book that lies on the table is mine.
The word 'која' here serves as a relative pronoun to specify the subject 'жена' (woman) within the relative clause.
Она је жена која увек доноси радост.
She is a woman who always brings joy.
In this sentence, 'која' functions as a relative pronoun to refer to the noun 'реченицу' (sentence) within the relative clause.