Debounce

A debounce system is a system that keeps a function from running too many times. It usually is used in a listener because it can be called many times while it's still working.

A debounce system usually works like this:

enabled = true					--default is true, so that the function works
function dosomething()
	if not enabled then return end		--if enabled is not true, then return without doing anything.
	enabled = false				--set enabled to false, because this function is already doing something.
	--stuff is done here			
	enabled = true				--open up the function to be called again.
end

Let's take a look at how debounce works in a real script. Here's the Local Gui script of the Rocket Launcher:

enabled = true
function onButton1Down(mouse)
	if not enabled then
		return
	end

	enabled = false
	mouse.Icon = "rbxasset://textures\\GunWaitCursor.png"

	wait(12)
	mouse.Icon = "rbxasset://textures\\GunCursor.png"
	enabled = true

end

So, when you fire a rocket, enabled is set to false and the reload icon is shown. Then the function waits for 12 seconds. During this time, enabled is false, so if the player tries to fire another rocket, the script won't run because the first line keeps it from running. After the 12 seconds are up, the reload cursor goes away and enabled becomes true again.