These two folders contain all the pages which will be displayed in the navigation menus on your website.
When you look at a website, you often find two index locations linking to pages in the website.
Often on top you’ll find Links to special pages, such as the contact page – and on the left links to information pages.
While the location of the Indexes on the Website depends on the theme you have selected, the principle is always the same: Pages contained in Navigation 1 will be shown in the location of Navigation 1; pages contained in Navigation 2 will be shown in the Navigation 2 location.
See also Custom Navigation.