This is the 2697th most frequent Polish word.
człowiekowi
"To the man/person" (dative form of "człowiek").
Here, 'człowiekowi' is in the dative case, used as an indirect object whom assistance is being given to.
Pomagam człowiekowi i udzielam wskazówek.
I help the person and provide advice.
In this sentence, 'człowiekowi' is again dative, indicating the recipient of the information.
Powiedziałem człowiekowi o tym spotkaniu.
I told the person about this meeting.
In this example, 'człowiekowi' serves the purpose of specifying the individual being explained the rules to, again in the dative case.