This is the 584th most frequent Lithuanian word.
žmogui
"Žmogui" means "to a person" or "for a person" in English.
In this sentence, 'žmogui' is in the dative case, indicating the indirect object of helping.
Visada reikia padėti žmogui, kai jis prašo.
You should always help a person when they ask.
Here, 'žmogui' is also in the dative case and shows the recipient of the speech act.
Aš sakiau tą žmogui, bet jis manęs neišgirdo.
I told that to the person, but he didn't hear me.
In this context, 'žmogui' denotes the intended target or beneficiary of the work.