A music system usually consists of a speaker system with built-in or external amplifiers, a mixer and a player (laptop, CD player, mp3 player) as well as the associated cables.
In principle, any PA system can be used as a music system. PA stands for Public Address and refers to loudspeakers that are designed to provide sound to a larger audience.
If you want to rent a music system, it is difficult for laypeople to choose the right music system or PA system.