Learn Polish: Dzięki! — Nie ma za co. - Thanks!

Yes, exactly! Dzięki translates to 'thanks' and is much more casual than dziękuję (thank you). You should use it with friends, family, and people you know well, but stick to dziękuję in formal situations.

How does nie ma za co translate to 'don't mention it'?

Literally, it translates to 'there is not for what' (as in, 'there is nothing to thank me for'). This is the most common and natural way to say 'you are welcome' or 'no problem' in Polish after someone thanks you.

Does nie ma usually mean 'there is not'?

Yes, nie ma is the standard Polish phrase for 'there is no' or 'there isn't'. You will see it used all the time when you want to say that something is missing, absent, or simply does not exist.

Why do we need the words za co in this reply?

Za means 'for' and co means 'what'. In Polish, when you thank someone, you thank them 'for' something. So za co points back to the reason for the thanks, completing the literal idea of 'there is nothing for what [to thank me]'.