This is the first puzzle in the hard difficulty.
You can either beat it legit or spam hints by pressing the "H" key on your keyboard or clicking on hint in the drop down menu on the upper left corner. Two tiles will glow once you activate a hint. Click on either of them to clear the set from the board. Repeat this until the puzzle is completed. If you run out of moves just load up a new puzzle on this board and try it again.