Why isnt this simple sound and light script working??????

you can't yield a coroutine from outside itself, so when you do coroutine.yield(Thread) it actually yields the MouseButton1Click thread

what you can do instead is make it so that if the lights are off, the loop continues running, but just makes it so that the lights have a brightness of 0

wait()
local RunService = game:GetService("RunService")

local Lights = true
local Brightness = 0.75

-- having a ton of different coroutines is kind of extremely nasty, and also less efficient than simply iterating over descendants each frame
-- plus they might be out of sync with each other

RunService.Heartbeat:Connect(function(timeDelta) -- timeDelta is the time passed since the last frame
    Brightness -= timeDelta/3
    if Brightness <= 0 then
        Brightness = 0.75
    end
    for _, light in pairs(workspace.Map.Lights:GetDescendants()) do
        if light:IsA("PointLight") and light.Name == "RLight" then
            light.Brightness = Lights and 0 or Brightness -- this behaves similarly to an if statement, so it's like if condition, then use value A, else use value B
			-- more specifically it uses the last value it evaluated but it's not really necessary to know that
        end
    end
end)

script.Parent.MouseButton1Click:Connect(function()
    -- there's no reason to have a debounce when the debounce is set back to false immediately
    for i,v in pairs(workspace.Map.Lights:GetDescendants()) do
        if v:IsA("PointLight") and v.Name == "PointLight" then
            v.Enabled = not v.Enabled
        end
    end
    if Lights then
        game.SoundService.Alarm:Play()
    else
        game.SoundService.Alarm:Stop()
    end
    Lights = not Lights
end)