If you'd like to prompt the Google Assistant to read off your text messages, you can say a variety of different commands, including "Show me my messages" and "Do I have any messages?" If you voice the latter of the two prompts, Google Assistant will only show you messages that you have not yet; consequently, the former command will showcase both read and unread messages. In addition to this, the "Show me my messages" prompt will also display a "Read messages" pop-up on your screen that will list all of your conversations in chronological order. Each conversation also features a Reply button, and tapping on this will take you to whatever app you're currently using as your default SMS client.
This is a feature that has been present within Google Now for a while now, so it's great to see that it's finally making its way over to the Google Assistant. Even better, this gives Android users yet another toy to play with seeing as how the Assistant is now on its way to all Marshmallow and Nougat handsets.