yeah its a safety so while holstering it or pulling it out it doesnt fire off. Its pretty simple actually....your finger has to fully depress that little lever before you can pull the trigger...this way if you just snag a corner of the trigger it wont pull.

Springfield Armory took it a step further when they did their knock off of the glock 22...they have that safety trigger...as well as another safety lever on the grip of the gun...you can pull the trigger unless both safeties were depressed on...quite smart....