Recently I was having a text conversation with a colleague, who shared a FedEx tracking number with me. I launched the Google Assistant and swiped up on the screen to reveal what it had found, and behold there was a link to track the package.
The Google Assistant supercharges what was once known as Google Now on Tap, a feature that never felt as useful as promised. But Google's smarts with this area appear even better, so you ought to try the Assistant out more often to see what it uncovers.
Just long-press on the home button (or say "OK Google") and swipe up. If there's something on the screen Google recognizes, it will give you context about it.
Note that voice questions will use what is on your screen to provide context, too. If you're reading an article about Guardians of the Galaxy, and say "what's the cast?" Google will be smart enough to know you want the cast of Guardians of the Galaxy.