Boxercise is a fitness class, not a fight. You move to music, as in aerobics, but you also punch, duck, and shuffle your feet the way a boxer does. People usually wear light gloves and hit pads, a bag, or just the air — nobody is trying to knock you down, and you are not scoring a match. Gyms like the name because it sounds tough and fun. It is informal fitness-world English, the kind you see on a class timetable. People who go want a sweaty workout with boxing-style moves; they are not training for a boxing career, though actually a few of the punches and footwork are real boxing shapes, just used for exercise.