A way of categorizing spells in some way.
Most of these descriptors have no game effect by themselves, but they govern how the spell interacts with other spells, with special abilities, with unusual creatures, with alignment, and so on.
A language-dependent spell uses intelligible language as a medium for communication. If the target cannot understand or cannot hear what the caster of a language-dependent spell says, the spell fails.
A mind-affecting spell works only against creatures with an Intelligence score of 1 or higher.