Yes, you can attach a suppressor to an A2 flash hider. The process is relatively simple and does not require any permanent modification to the firearm. There are a few different ways to do it, but the most common method is to use a threaded adapter that goes over the existing threads on the barrel and provides new threads for attaching the suppressor.
Suppressors work by trapping and redirecting the hot gases that are produced when a gunshot is fired. This results in a reduced muzzle flash felt recoil, and noise output. These days, they are commonly used by military personnel, law enforcement officers, and private citizens who want to reduce the noise generated by their firearms. While they can be attached to various types of firearms, they are most commonly used on rifles.