This is the 163rd most frequent Azerbaijani word.
onlara
"Onlara" means "to them" in English.
In this sentence, 'onlara' is used as the dative case of 'onlar' (they) to indicate the indirect object, showing to whom the action is directed (to them).
Kitabları onlara ver.
Give the books to them.
Here, 'onlara' also acts in the dative case, expressing the entity towards whom the belief or trust is directed (we believe/trust them).
Biz onlara inanırıq.
We trust them.
'Onlara' in this sentence indicates directionality or the target of the look, again emphasizing the usage of the dative case to indicate the indirect object.