Hi Sam, A magazine disconnect (also sometimes called a magazine safety) in a handgun is a mechanical safety device that prevents the firearm from firing when the magazine is not fully inserted. Essentially, even if a round is chambered, the gun will not fire if the magazine is removed or not properly seated. Its purported purpose is to render the firearm inoperable, especially when a user intends to disarm the weapon quickly in a stressful situation.
Stay safe & have a great day!