how do you detect when a function is called?

function test()
game.StarterGui.ScreenGui.Enabled = true
end

how would I have a script that activates when this function is called

You cant signal once a function is called, but you can enable a script inside of the function.

function test()
youScript.Disabled = false
game.StarterGui.ScreenGui.Enabled = true
end

i hope you can understand this!

very very very easy!

local script = script.Parent.Parent

local function enableScript()
      if  script.Disabled then
           script.Disabled = false
     end
end

enableScript() -- so that we can calls the function since ummmm function donte run automatically!