Site usage is like a dashboard to of any site in the SP Online. How many Visit, How Many new items and all highlighted items, documents show to admin. It is very helpful for the site admin to draw a clear picture for the content and statistics.
Previously these reports show on the site content page, in the modern site in SharePoint and a site owner would see site usage information at the top of the Site contents page.
Now MS has established a dedicated page for the site usage. They have moved this analytics portion to a dedicated page. The Site contents page maintains focus on access and management of content (lists, libraries, pages, etc.), and provides insights into how your site is being used via this new Site usage page.
his message is associated with Office 365 Roadmap ID 16048.
It ‘ll begin gradually rolling this out in the following days (June 29 17), and the rollout will be completed by the end of July.