The URL is https://www.peterbe.com/rss.xml
An RSS feed is a XMLish summary of what is being updated on a website. It's standardised so it should be possible to view it from any program or web application.
My recommendation for an RSS feed viewer is Feedreader which is free and works really well. Download it, install it and enter https://www.peterbe.com/rss.xml as a new feed.