This release does not have a Play Store Description, so we grabbed one from version 1.0.1920:

Welcome to a sneak peek of our new mobile browser.

We know a little something about making game-changing web browsers. That’s why we’re excited to give you early access to Firefox Preview, a sneak peek of our new mobile browser. Built on GeckoView, this is our fastest Android browser yet. We’ve turned up the volume on everything you expect from Firefox: ease of use, safety, choice, control and privacy.