"Do not take this, take something else."
Translation:Nie bierz tego, weź coś innego.
This is an example of two irregular verbs (there aren't actually that many of them). „Brać” is the imperfective verb, but its perfective equivalent is „wziąć”. They also have some exceptions in conjugation.
For a full list of irregular verbs see https://pl.wiktionary.org/wiki/Aneks:J%C4%99zyk_polski_-_czasowniki_nieregularne