Block bad referers

When you type the address of a site in the address bar of the browser, there is no referer, it's a direct access.

The referer is the site from which you arrive. If you make a request in a search engine, for example on Google, by clicking on a link in the results, the referer will be "".
If my site has a link from a malicious site, then I can decide to block these visits. Let's say that "" links to my site then I want to block "".

Add an address per line in the Referers List section.
Google in the "Search Console" tool provides the list of links pointing to your site.