The short answer is that it’s all code - XML to be exact!
This little scroll-y block of text is an example of an RSS Feed. RSS stands for Really Simple Syndication, and it is the web content syndication form that allows for the function of podcast distribution.
Every podcast has an RSS Feed (though not every RSS feed is a podcast). When you publish a new podcast episode, in essence you are adding a new XML <item> to your RSS Feed in the form of various <enclosures> which contain metadata about your episode. Subscribing applications such as Apple Podcasts or Spotify will scan your RSS ffeed for updates, and then pull all the new metadata once they have been published to make available to listeners and subscribers.
Thanks to entities like the RSS Advisory Board and the World Wide Web Consortium (W3C) there are standards for what an RSS Feed should contain so that they can be uniform enough to be used widely across the internet as a content delivery method. Due to these standards there are certain <tags> or <enclosures> that have to be in your feed in order to be read and accepted by Podcast Apps.
This includes things like:
Podcast Title; <title> </title>
Description; <description> </description>
Subtitle/Teaser; <itunes:subtitle> </itunes:subtitle>
Series Image; <itunes:image> </itunes:image>
Show category; <itunes:category> </itunes:category>
Clean/Explicit; <itunes:explicit> </itunes:explicit>
Copyright; <copyright> </copyright>
A Published Episode
Having these elements in your feed ensures that your feed is “valid” and will be accepted by the major podcast apps when you’re ready to submit - and that your subscribers will get all your new content as you publish it!