In the list of recent apps, touch the app's icon at the top of the preview to see
and
.
Be sure to touch the app's icon instead of the preview, which opens the app.
Drag the divider all the way up or down.

With some apps, you can watch video in a small, movable frame while you do other things. Use it when navigating with Google Maps, too.
When you’re playing a video or navigating with Maps, go to the home screen or app you want to use.
The video (or navigation) shrinks.
You can drag the video (or navigation) anywhere on the screen.
To see all apps that support Picture-in-picture: