Could not be simpler. It's like one of those Pelmanism card games - Concentration, Pexeso, 神経衰弱, Match-up or whatever you call it. Just find matching pairs.
Note: tiles are matched in pairs, in sequence => [1st to 2nd], [3rd to 4th]... and so on. Say you flip one, X, then a second, Y, if they don't match they flip right back. That's one 'move', which implies that the pairing stars anew. If you think the next tile you then flip, Z, matches the second you just saw,, Y, you need to flip that tile, Y, next.
Use the 'Edit' button to change the characters when done with this set. Or, of course, you can use the game to help memorise words in a different language, or indeed, anything else you might use flashcards for. Kids can pair emojis with second-language words. Endless possiblities!