A sitemap is one type of file where you can list the web pages of your site to inform Google and other search engines about the organization /Set-up of your site content. Search engine web crawlers like Google-bot read this file to more prudentially crawl your site.
Difference between XML sitemap and HTML sitemap
The XML sitemap is the search engine friendly, where HTML sitemap is User-friendly.
XML Sitemap displays content and organization of content of a website in search engines, while HTML Sitemaps will reflect the method that a visitor works through a site that gives them a great extension on any site.
Benefits of having a proper Sitemap for your website:
1. Helps Google find your content
2. Having your site changes crawled quickly
3. Better crawling and indexing of your website
4. Get better reporting on your website