It’s a method of frying in the sense that “stir frying” is a method of frying. Sauteing is frying in a pan, such that you’re turning the stuff over regularly by this tossing action.
One of the outcomes of sauteing is that your stuff gets browned in a randomized, pleasantly-varied manner, since with each toss-and-catch some items flip over and others end up on the same side again.