Websites often have some method for notifying users when they publish new content. Typically, this is done by giving the website your email address, so that it can send you email notifications, or by receiving push notifications to your browser or device. Another method is RSS, though it is quite obscure these days. This is unfortunate, because it's better for user control and privacy than most other methods.
An RSS feed is a file stored on a website that contains a machine-readable list all of its recent updates and notifications. To subscribe to an RSS feed, you copy the link to this file (for this website, https://marianicolae.com/rss.xml) and enter it into a special program called an RSS reader. This reader re-downloads the feed at regular intervals, and notifies you when there's something new. In that sense, it's like it automates the process of repeatedly refreshing the page in your browser.
Compared to other methods for subscribing to a website, RSS has multiple benefits for the user. You don't have to give the website your email address or make an account with them, so it's good for privacy; all the website sees is your IP address, just like if you were simply browsing the site. RSS is an open standard, which means that you're free to use a reader of your choice. Unsubscribing from an RSS feed is as simple as removing it from your reader. Finally, an RSS feed is a simple chronological list that is the same for every subscriber, so there's no algorithmic curation to keep you hooked or influence what you see. Overall, RSS is very good for user control and privacy, which is a big reason why it has fallen out of use; compared to other forms of subscription, it doesn't allow the website to track you, spam you with promotions, or manipulate you.
If by now you're ready to get started with RSS, you might want to know that many email client applications have RSS reader functionality built in, so there's a good chance you don't even need to install a new program. Personally, I use Thunderbird for both email and RSS.