Every site wants a good search engine ranking. The metatag modules is needed for that as well as this module. A sitemap is een collection of the nodes you want to be indexed by the search engines. Usually this sitemap is on the front page. Search engines find them en start indexing. This module is Drupal 8 only and is built to deal also with multilanguage sites. Ther is an other XML sitemap module. Compare them...
You see 3 tabs in the configuration. The first one allows you to regenerate the sitemap manually. Default is regenerated on every cron.
In the second tab you choose what you want to display. Content and menus for example.
In the third tab you can point to specific pages. Here the front page has a priority 1. This is the highest importance. Default you can add every content type to the sitemap. With this method you can add views and other pages.
Every content type has his own settings of priority.
When you visit yourdomain/sitemap.xml you can see the sitemap. Browsers can not deal with them, so you have to look in the source code.
In the source code there is more structure...Look how this module deals with the multilanguages..
Now you have to put the link on your front page. Making a block is the easiest way. Now every search engine will find the structure.. Some people hide the sitemap link by giving it the same color as the background...Engines do not look at the color...