In the world of weight lifting, cutting refers to a period where you sustain a calories deficit while keeping your proteins intake. The goal is to lose the fat you've gained while bulking in order to reveal the muscles you've built.
This mean eating less, aiming at about 30x your weight (in kilo) of daily calories, and adjusting until you look fit enough. You also keep training as usual while cutting, so you'll probably need protein supplements to keep and even grow more muscles while burning the fat you've stored.