My son is going to be 11 soon and he throws a cutter. Started working on it last summer.
A cutter is a essentially a fast ball with your fingers on the ball differently and apply different finger pressure to the ball at release. Same as a 2-seam'er and a change-up. You throw with the exact same motion and only finger placement and finger pressure should change (ok.. slight pronation at release on circle change but not drastic) My son's cutter will move about 4-6 inches. The catcher on his team loves to call it... so funny.
Freshman... sure.. go ahead and learn it if he is commanding his fastball.... IMO