The so-called quick release system is a component of your weight belt. In emergency situations, you can drop it with just one hand movement.
When should I use the quick release system?
A typical emergency would be when your buoyancy compensation jacket is damaged and the air flows out uncontrollably. In this case, the weight belt could pull you uncontrollably downwards. By pulling on the buckle, it falls off and you are still stabilised.
But beware: You should really only drop the belt in emergency situations! Because by doing so you can definitely ascend faster than it would be healthy. Thereby the risk of a barotrauma or decompression sickness increases.
Find the best Dive Professionals, Dive Centers and Liveaboards on rateyourdive.com