Complex sentence: A starting pistol or starter pistol is a blank handgun that is fired to start track and field races, as well as competitive swimming races at some meets, and the sound of the gun going off serves as the signal for the athletes to begin the event.
Split into simpler sentences: A starting pistol or starter pistol is a blank handgun that is fired to start track and field races, as well as competitive swimming races at some meets. The sound of the gun going off serves as the signal for the athletes to begin the event.