How To Disable Player Vs Player But Still Do And Take Damage From NPC's?

This would be greatly appreciated if anyone could help. I also would need to know where to put the script (If Needed). So if anyone could help me thank you.

https://scriptinghelpers.org/questions/35875/how-to-disable-pvp-but-still-be-able-to-kill-zombies

Just make a CanPVP bool value, if it is set to true pvp will be disabled ( player wont get damage by any other player)

-------- ur function
local CanPVP = script.Parent:WaitForChild("CanPVP")

if CanPVP.Value == true then
------ damage

else 

---- damage = 0