The Refinement web part is used to configure refining, categorization, sorting, and grouping options for search results. You can either use a managed navigation term set or configure a list of refiners with the Choose Refiners... button. Available refiners can be seen in the following screenshot:

After configuring the various web parts on the page, you can check in and publish the page to make the changes available to users. For more information on configuring the Refinement web part, please go to https://docs.microsoft.com/en-us/sharepoint/refinement-web-part and https://support.office.com/en-us/article/about-configuring-the-refinement-web-part-7cef67e8-b992-4659-b21a-ba534eea102e.

Next, we will explore some reports and logs related to Search.