That entire industry is a toxic hell-scape. It went downhill real fast once they realized that helping people actually find each other also means they stop being a customer. So now these apps tune their algorithms to either ping-pong you between hope and misery, or find you one-night-stand after one-night-stand. They only really work for people who want casual encounters, because they come back for more. Looking for something serious, and you might as well eat shit and die, because you're not using the app in a way that's profitable.
They show each user everyone except the people they'd actually want to meet and get to know. You won't even get lays with people you might actually like, because they want you back to swiping for another person asap.
In this case, the message is displayed after you swipe left (reject) another date seeker.
It claims you “missed a match”, which is kind of insulting because it implies the user is a slut whose main criterion is whether the other person is interested.
It means someone you swiped away (as in rejected/wasn't interested) later swiped you right (as in is interested). Dating apps nowadays have a paid feature where you can "rewind" and change which way you swiped someone.