The term 'GYM EXERCISE UNIT' is a job description for a Representative, which is abbreviated as REP with 3 letters. A Gym Exercise Unit Representative is responsible for providing customers with information about gym equipment and exercise units. They must be knowledgeable about the different types of machines and their uses, as well as how to properly use them. They must also be able to answer any questions customers may have about the machines and provide advice on how to use them safely and effectively.