First, check the "Likes You" section () to see if anyone has indicated interest in you!
The "Likes You" section mirrors the functionality of the "Discover" section (where you make a decision before seeing the next person.) So, when someone has indicated interest in you, you have to make a decision about whether or not you're interested in them before seeing the next person.
(Curious about our reasoning here? We had a lot of users that were just basically hoarding incoming likes or continuously coming back later to review profiles, but not actually taking action. We wanted to encourage users to take action so that they can start going on dates!)
If you're interested in the person who liked you, tap - you don't have to send a message to match, but why not get the conversation started?