Debounce | having trouble :( ?

A simple fix; the only problem with your code is that you defined debounce too late in the script. You need to define it before the Touched listening event, and you need to make the conditional activate when the debounce is true like so:

game.Players.PlayerAdded:connect(function(player)
    local debounce = true
    script.Parent.Touched:connect(function()
        local plrstats = player.leaderstats.Timer
        if debounce then
            debounce = false
            plrstats.Value = plrstats.Value +100
            wait(2)
            debounce = true
        end
    end)
end)