This article is called "Introducing new Colorways for Firefox 94" but doesn't explain what the feature does, beyond being "a new feature that allows our users to express their most authentic selves and to bring them joy while browsing the web".
I went to mozilla.org and, in two clicks, reached the page for "Firefox for Desktop". It has a section with "Latest Firefox features", one of which is "Personalize your experience with new colorways"... But that text is not clickable, so I'm not getting more information there either.
I guess Mozilla doesn't want me to know what "Colorways" are.