Most video services (Netflix, YouTube, etc.) offer Like and Dislike buttons, mostly to train the magical algorithms about what you like to watch. Hulu has always lacked this functionality, only giving viewers a button to stop recommending a certain show. That's finally changing, as Like/Dislike buttons are now rolling out to all platforms, including Android.
You probably know what Like and Dislike buttons look like, but Hulu has provided a visual representation just in case.
The buttons aren't appearing on my phone quite yet (even though I'm on the beta channel), but once they're rolled out to everyone, they should drastically improve Hulu's recommendation engine. On a somewhat-related note, the company also said Hulu's search functionality should get better over the next few months.