this is my script to try but I cant find out how to add to the players health?
local UserInputService = game:GetService("UserInputService")
local debounce = false
local heal = 50
UserInputService.InputBegan:Connect(function(input)
if input.KeyCode == Enum.KeyCode.R then
local name = game.Players.LocalPlayer
local player = game.Workspace:FindFirstChild(name.Name)
player.Humanoid.MaxHealth = 125
player.Humanoid.Health + heal
end)

2 comments
try setting player.Humanoid.Health to itself like player.Humanoid.Health = player.Humanoid.Health + heal
Instead of "player.Humanoid.Health + heal" you can do "player.Humanoid.Health += heal"