The number of exercises that you perform in a row without a break is called repetitions. The term repetition, also know as rep, defines one complete motion of an exercise. Example: one deadlift, one bench press... A set on the other hand is a series of repetitions performed sequentially,example: 8 deadlift s performed one after another without a brake. The repetition maximum (RM) is your personal best or the most you can lift once in a single repetition of an exercise