how do i make the brick change color on click and make the sound stop playing if clicked again?

To change the color of a brick correctly you need to use the Color3 method. If you are using a RGB color you can also use Color3.fromRGB(x,y,z).

As for the sound stop playing after clicking again you can add a debounce.

In the end your script would be:

local status = false

function onclicked() 
    if status == false then
        script.Parent.ClickDetector.MaxActivationDistance = 0 
        script.Parent.ClickSound.Playing = true 
        wait(6)                                  
                script.Parent.ClickDetector.MaxActivationDistance = 32 
        script.Parent.ClickDetector.BrickColor = Color3.new(212,0,0) -- or Color3.fromRGB
        status = true
    end

    if status == true then
        -- Stop playing and do the rest
    end

end 

script.Parent.ClickDetector.MouseClick:Connect(onclicked) 

j

local Toggled = false

function OnClicked()
    if not Toggled then
        -- Alternatively, you can use Color3.fromRGB(212, 0, 0) instead. Color 3 values must utilise / 255 unless you're big brain.
        Toggled = true
        script.Parent.ClickDetector.MaxActivationDistance = 0
        script.Parent.ClickSound:Play()
        wait(6)
        script.Parent.ClickDetector.MaxActivationDistance = 32
        script.Parent.ClickDetector.BrickColor = Color3.new(212 / 255, 0, 0)
    else
        Toggled = false
        script.Parent.ClickSound:Stop()
    end
end

script.Parent.ClickDetector.MouseClick:Connect(OnClicked)