This screenshot shows the Customize dialog box which has tabs for Commands, Toolbars, Tools, Keyboard, and Add-ins and Macro Files.
In this example, the Commands tab is open. It contains a category drop-down list displaying File and a collection of buttons which would be appropriate to the file menu (i.e. save, open, print).
The Commands tab contains a Show Menus for drop-down list set to Current Editor. There are additional buttons to Modify Selection or Reset all Menus, as well as a close button.