Airsoft is kind of like paintballing, except instead of shooting paintballs you shoot small plastic BB‘s. They‘re all under 500 feet per second (otherwise in Canada, they‘d be considered a firearm), so as long as you‘re wearing goggles and some other protection, they won‘t hurt you.. They‘ll just sting.
The really neat thing about airsoft is that a lot of the weapons look very realistic. So, basically, If you can‘t get a real replica (replica weapons are prohibited) and can‘t get the real weapon (i.e. it‘s prohibited, or very expensice) you can get an airosft version...