Some websites offer a series of regularly published articles called an RSS feed, Atom feed, web feed, news feed, or feed, and you can subscribe to feeds in Safari. When you subscribe to articles while visiting a website, Safari asks you to confirm that you want them to appear in the shared links sidebar.
While viewing a webpage, click the Share button 
in the toolbar, then choose Add Website to Shared Links. If you don’t see this option, the page you’re viewing doesn’t offer a subscription (or feed).
You can also click a subscribe link or feed link if the webpage has one.
Click Add to accept the subscription and start receiving articles from the website, or click Cancel to decline the subscription.
To see the articles you’ve subscribed to, click the Sidebar button 
in the toolbar, then click the Shared Links button 
.