Yes the block “call.Admob1.loadAd” will be same on every screen, you have to use this block to load ads.
And you do not need to hide any component when you switch a screen, let it be admob banner or any other component, all components will hide automatically when you navigate to another screen.
See also How to switch screens correctly
And Admob AD Unit Id is the Code that google provide you to integrate in your app to show ads its like ca-app-pub-3940256099942544/6300978111
Hope am clear enough 