You're probably confused by the weird floating squircle that has what looks like someone knocked over a wifi symbol over in it. This page is here to try and explain what that is (even though I'm not the best at explaining things imo).
Acording to RSS.com, RSS stands for Really Simple Syndication. It's pretty much a way to throw information from a site at a bunch of people, kind of like a personalized newspaper stand for the people who are using it to get that information, or subscription emails. Though instead of sending out emails to a ton of people, meaning I'd have to have a list of email adresses that belong to other people just sitting around somewhere, I can just update a file on my site and have people save the link to that instead!
Of course you'd need a way to see the information and set up a digital newpaper stand for yourself since you can't have your inbox do that for you. Though I think we all agree that trying to orginize our emails is a pain in the ass, even with using 100+ filters to clean up spam automaticly...
Anyways, to actualy get RSS feed updates, you'll need an RSS feed reader! Personaly I'm using the Feedbro extention (Firefox | Chrome) since it's pretty simple looking and I can just keep it pinned. This will be like the actual stand where the news stuff goes. You'll also want a link to whatever RSS feed you want to see, for example this one here which is mine. Some pages may act as a download if you click their link, so you'll want to right click to copy the link instead.
In whatever RSS feed reader you've decided to use, you'll need to click on an add feed button. Feebro's looks like a tiny RSS logo with an even smaller plus on the corner. Now put in the url where it asks you for it and fill out any other required information you need to give it. For mine you really only need the url.
Tada, you now have a place to check for site updated from your favorite sites!
If you're looking for updates of other Neocities sites and can't find one on the site itself, Neocities provides one through the share link on a user's profile. I will mention that this will be for every update, including if the person just went in and fixed a single typo on a page.
If you'd like to make an RSS feed for your own site you can use this guide I found that I used to help me make mine!