how to make block damage once roblox code example

Example: how to make a Damage Script in Roblox studio

local rarm = script.Parent:FindFirstChild("Right Arm")
local larm = script.Parent:FindFirstChild("Left Arm")

function dmg(hit)
	if hit.Parent ~= nil then
		local hum = hit.Parent:findFirstChild("Humanoid")
		if hum ~= nil then
			hum.Health = hum.Health -10
		end
	end
end

rarm.Touched:connect(dmg)
larm.Touched:connect(dmg)
--Made By Rigby#9052 on Discord