An XML sitemap is a file that lists pages a website wants search engines to know about. It is like a map of useful rooms in a building, shared with someone who is learning the layout.
The list can help a search engine discover pages, especially on a large or new site. It does not mean every listed page will appear in search results.
Keep the file limited to real pages you want people to find. A sitemap is not a replacement for clear links between pages or for useful page content.