If you're printing negatives and the print comes out too XXX, then by adding colour XXX filters (or -YYY and -ZZZ) in with the negative, you're removing XXX from the print, because you're adding it (proportionally) to the light.

In this example XXX, YYY and ZZZ are three arbitrary primary colours. Of course, if you're printing in Cibachrome, then if the print comes out too XXX then you add -XXX filters in.