How do i know if I can use a "free" asset for commercial purposes?

I’m gathering some resources/assets that im gonna use for the game that im planning to build. I just wanna know if im gonna be able to use the “free” assets to build a game for profit. Im just not quite sure about this one.

Does “free” mean im free to use it for a game that will be built for profit? -except sell the asset it self(i understand that)