Site map is in Site > Site Settings > Site Map.
Search engines, such as Google use site maps, in order to know what pages are published and the structure of your site. You can submit this site map URL into Google for it to index your site map and is a good policy.
Site map is in site > site settings > site map.
At the first time, you can see the button 'Create Sitemap'. When you click on it, the site map will be created as an XML file.
Once the site map is created, you can copy the URL use it. The site map can be recreated whenever you need.
You need to recreate the site map when you create a page or unpublish a page that you does not use on your site. If you would not like to show a page, unpublish the same and recreate the site map. Then it will not show in the site map.