SearX is a metasearch engine. That means it returns results from other selected search engines. It's accessible via an onion address and provides a private search ability. Really the only advantage it gives you over searching directly from a Tor browser is the ability to customise your search experience.
In terms of security both the connection between you and the server, and the outgoing connection from the server to other search engines are onion routed. This should give you a reasonable level of search privacy.
Once it has installed go to *About* on the *Administrator control panel* and look for *searx*. Take a note of the onion address, and you can then enter that into a Tor compatible browser. Go to *Passwords* on the *Administrator control panel* and select *searx*. This will give you the login password for your search site, and it prevents millions of random internet users from using your site as their default search engine and ruining the performance of your system.
It's also possible to customise the background image if you go to *App settings* then select *searx*.
