In this instruction is following Goals is intended.
Page Meta is a set of data (title, link, class, keywords, descriptions) that belongs to an object of the website (product,brand,category,content,etc.).
All metas is listed under Page Meta admin section. (Admin panel > Left menu > PAGE META > All Link)
it is category of a meta to classify by its type. Below is the list of default Meta Types.
Meta Type - id : desctiption
Static - 1 represents static pages.
Product - 4 : represents product metas.
Product Categories - 5 : represents product categories metas.
Content - 6 : represents content metas.
Content Categories - 7 : represents content categories metas.
Content Type - 8 : represents content type metas.
Properties - 10 : represents product properties metas.
Brands - 11 : represents brand metas.
Meta Routes - 9 : represents meta routes metas that framework recognizing for dynamic url. ( category.html/page/(:num) )
Following Link includes enough detailed instruction to comprehend Main Menu.
Top menu Links
It is the links next to login link on the top of default cart21. The Plugin "Links on Top" is a static plugin that enable admin user to show Top menu Links on a page position.
Where admin user select a meta link as Top menu link?
It is the links on the footer of default cart21.
Where admin user select a meta link as Footer link?
Screenshot : sorting admin section for Footer links, Top Menu links and Main Menu link.