They are above the employees and below the C suite. You probably could just call them "managers" with little loss of meaning. But the term "middle management"

They are above the employees and below the C suite. You probably could just call them "managers" with little loss of meaning. But the term "middle management" can connote a kind of useless that makes them different from "front line managers". The difference seems to depend on how useless your front line managers appear to be.