Hi, i want to know if there is a way to make a gun that follows your mouse, like in cor5 of litozinnamon that the gun follow your camera, and my second question is, what is addDebris() (or something like that)?
Yes, there is a way. Otherwise you would not have seen it. As for how, that is for you to discover. Perhaps you have something in mind you would like help with? Such as CFrame, and it's second parameter?
tool.Handle.CFrame = CFrame.new(tool.Handle.CFrame.p, mouse.Hit.p)
Debris is a service.
AddItem() will add an instance to the service and ultimately destroy itself after it's assigned lifetime.
game:GetService("Debris"):AddItem(game.Workspace.BasePart, 5)