By now, all of you have undoubtedly seen Google's "featured snippets," which are those little paragraphs of text that show up first when you're looking for answers. Google is now testing a "Hear this out loud" button that will read said snippets to you out loud.
— Barry Schwartz (@rustybrick) May 26, 2021
The button in question will, as the name implies, allow you to hear the snippet read to you out loud. The usefulness of this is debatable; after all, the snippet is intentionally short and to-the-point already so as to be easily readable.
Looking at the Twitter replies to the author of the SE Roundtable article, it appears that the feature is being tested in India first. The author was also unable to replicate the functionality, and I wasn't either. Whether the feature becomes official or makes it to other regions is still up in the air.
- SE Roundtable