@WeirdWriter I didn't understand them either until I added myself to one a couple weeks back (despite being online through the 90's when webrings were everywhere).
Basically they're a list of sites that share some commonality. Each site in that list will usually post a link to that list, and there is usually a way to link to the website before you and after you as "next" and "previous".
E.g., https://natecox.dev is part of the human first webring, which is a list of sites that use no GenAI in their construction. You can see the links in the nav for my site.