Menus have traditionally been the way to navigation.
Nowadays more and more navigation facilities like Tabs, ViewPager and BottomNavigationBar are available.
However, menus are probably still the easiet and most popular and advantageous. This is because of the following:
They are easy to use for users with respect to navigation.
Menus can confine more menu items in a small space compared to other navigation utilities like the navigationview, tabs and bottom bar.
Menus are typically easy to customize as we represent them via XML in many cases.
Let's look at some examples.
ContextMenu support has been in android since API level 1. It's an extension of menu and implements Menu interface. It's actually an interface itself.