Just last month, Google brought WiFi Assistant to all Nexus devices that don't use Project Fi, and to other countries. It was an extension of a feature that was previously only available to Project Fi users. Essentially what it would do is automatically connect to known WiFi networks and public hotspots (like those free WiFi networks found at Starbucks, McDonalds, Burger King, etc) and it would secure them by using a built-in VPN. It's a great way to stay away from your data limit and any overages that you might encounter from your carrier. However, Google just made this feature even better.
As of the latest version of Google Play Services - which is v9.6 for those wondering - you can connect to any unsecure network and the WiFi Assistant is able to secure it. Previously, it would only be able to secure networks that it recognized. But now you can connect to that unsecure network at your favorite Chinese restaurant or even the airport and have Google secure it. The process is quite simple, and makes it easy for anyone to use. When you connect to an unsecure network, you will see a notification appear in the notification shade. Just tap on the notification, then tap on the "Secure" button in the pop up window. And that's it. There's nothing else that needs to be done here.
It's great that Google added this feature to WiFi Assistant and even better that they made it super easy to use. Even those that may not be technology literate will know how to use this feature. Which is definitely a great thing. And yes, Google is still securing networks through their own VPN, as they have been doing with Project Fi since that launched. Google Play Services v9.6 is what is needed to get this feature working on your Nexus device (it doesn't need Nougat, it does work on Marshmallow just fine). The update to the newest version of Google Play Services is currently rolling out and it should be on everyone's devices within the next few days. Remember that this only works on Nexus devices and not all Android devices, yet.