How do you keep a sound from repeating?

You can use a debounce to stop it repeating. For making it start/stop when you touch it, use a variable to make the variable true when the sound is playing.

db = false --Debounce variable
playing = false --Checks if sound is playing (there's a property in Sound, but it's buggy)

script.Parent.Touched:connect(function(hit) --Touched event's function.
	if db then return end --Stops the code if db is true.
	db = true --Sets db to true so the code doesn't run multiple times.
	--Optional check to see if hit is a player's character here.
	if playing == false then
		--Play your sound here.
		playing = true
	else
		--Stop your sound here.
		playing = false
	end
	wait(1)
	db = false --Waits 1 second before allowing someone to touch the brick again. Important, otherwise nobody will be able to touch your brick afterwards.
end