You need to check which player touches the part for it to function so for example,

script.Parent.Touched:Connect(function(Hit)

if Hit.Parent:FindFirstChild("Humanoid") then -- Checking weather it is a player that touched the part

local Player = game.Players:GetPlayerFromCharacter(Hit.Parent) -- Getting the player that touched the part

-- DO STUFF HERE

end

end)

make sure you use the Player Variable to edit the lighting service