There are a few WCAG success criteria that I've always been intimidated by (I'm looking at you Parsing). As a way to get past this intimidation, I'll attempt to break each one down, starting with success criteria 1.3.1 Info and Relationships:
Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.
I can't be the only one who reads this and their mind goes numb. So what is this really saying?
This refers to the page's content (information), how that information is organized (structure), and how each piece of content is associated with each other (relationship).
Yikes.. This is a very complicated way of saying delivered in a way or format that is perceivable to the user. To simply that last part even further (for someone who doesn't know WCAG's POUR principles off hand), I might say "...format that is preferred by the user." I think that encompasses the fact that a user would likely only prefer a format that is perceivable to them.
Okay, I see "programmatically determined" everywhere in WCAG. I wish we'd stop using it because it just isn't easy to understand (I'm still struggling to find a way to describe this as I type this). I interpret this phrase as the broadest way to describe a piece of software that retrieves and presents websites to users, whether that software is a web browser, media player, plug-in, an assistive technology, or a combination of these. I'm going to embrace the vagueness of "programmatically determined" and would simply replace this text to "technology."
This one is self explanatory, but I think it could easily be missed since it is at the end (see mind numbing comment from before). This section is calling out that compliance can be met by simply addressing the structure or relationship using text! I think it is super important to call this out. Let's say you're new to this accessibility thing and don't know where to start with presenting your page's information to a screen reader correctly. You can technically meet compliance by numbering your headings explicitly in the visible text. This obviously doesn't for everything, but it could be a baby step.
If I had to rewrite this success criteria into something a little more user friendly, I would say:
Content, how that content is organized, and how each piece of content is associated with each other can be delivered in the user's preferred format using technology; or it is mentioned explicitly within the content.
Introduction to my most recent accessibility side project