I believe this audit is checking if any anchors, <a href=”…”>, on the page are missing an accessible name. For instance, if you have an anchor that just contains a background image, it will be announced as “link” to a screen reader, without any context as to where the link goes to.
I believe it also checks against a list of words that make for bad link text in screen readers, e.g. “here”, “learn more”. I have a post that should be going out hopefully today that explains this a bit better.