how to make a safe mode button or area?

i am making a gun game and i am looking to find a way to go in safe mode, basicly not loose health from being shot can anyone help me with this?

Not exactly sure what you're trying to accomplish, but I think it could work if you set their health very high.

player.Humanoid.Health = 1000000000000000

If you give me a bit more context as to things like how they will go into this safe mode, etc, then I can help you a bit more.