There is a finite amount of room for links on the left-side navigation menu of your website. What do you do when you have more pages in your website than you have room in the navigation menu for links to each of those pages? You create what might be considered a sub-menu or an extension to the left-side menu.
The simplest Index page (a list of links on a page) can be created using the List page type. With the List page, you can create an index or list of links to many other pages. The limitation is that you can have only one column of links. What if you want two or even three column of links? Then you can use one of the Blank page templates.
Index Page with a Blank Page Template
To create an index page using a Blank page template, you can either pick one of the two-column Blank page templates - Blank (two-column), Blank (two-column plus top area) and Blank (two column plus bottom area) - or use the Blank (Single area) page template and use a table to create multiple columns.
Please read how to create such a page - Blank (Single area), Blank (two-column), Blank (two-column plus top area) and Blank (two column plus bottom area) - and how to use tables to create multiple columns of information (such as columns of links). Once you have created a Blank page template with multiple columns using a table, you can find out how to add links in a Blank page template.