A compensator on a handgun is something that vents the hot gasses and pressure upward, which pushes the barrel downward. This is a way of reducing muzzle rise or muzzle "flip" which is the upward component of recoil.
(The reason a handgun flips upward when you shoot it is because the recoil is generated in the barrel, and the barrel sits above the place you grab the gun.)
A compensator is sometimes called a muzzle brake.
The same effect can be achieved by "porting" a gun's barrel, which means to drill some small holes in the top side just a short distance back from the muzzle.
Chat with our AI personalities