Entries on the Components menu and its sub-menus may be translated using a mechanism that allows translators to include translations for third-party developer extension entries.
A language INI file in the administrator/languages/<lang> directory, called <lang>.<component>.menu.ini will be loaded when the administrator menus are built and should contain language replacement strings for the menu item and its sub-menus.
For example, the Banners component, com_banners, has a menu translation file in administrator/languages/en-GB called en-GB.com_banners.menu.ini in which you will find:-
COM_BANNERS=Banner COM_BANNERS.BANNERS=Banners COM_BANNERS.CLIENTS=Clients COM_BANNERS.CATEGORIES=Categories
The first of these strings replaces the menu item in the Components menu. The other three replace sub-menu items within the Banner entry in the Components menu.