This is the 12th most frequent Serbian word.
које
"Које" means "which" or "that" in English, used as a relative pronoun in Serbian.
In this sentence, 'коју' is a relative pronoun in the accusative case, referring to 'Девојка' and introducing a relative clause.
Девојка коју сам срео на путу била је баш љубазна.
The girl whom I met on the road was very kind.
Here, 'које' is a relative pronoun in the nominative plural form, agreeing with 'Књиге' and introducing a relative clause.
Књиге које си донео су веома занимљиве.
The books which you brought are very interesting.
In this example, 'које' is a relative pronoun in the nominative plural form, matching 'кошyље' and introducing a relative clause.