How is it possible for metals to have positive charge carriers?

t.dett

Sorry if this is a noobey question, but I've been wondering how it's possible for metals to have 'holes'. After all, there's no 'forbidden gap' in the band gap theory, so I don't see how metals like copper have positive Hall coefficients and positive Seebeck coefficients/thermopower.

Could someone please explain it to me, or even better, give a link?
I can't find anything on holes that isn't about semiconductors.
Thank you so much for your time, in advance :)