Click the button to begin playing. You can pause the game at any time with the same button. It will pause automatically if nothing happens for a while.
Click on a word to hear it. Now click on the second copy of this word to make the pair disappear. You can listen again to the last word by clicking the replay button. If you don't want to hear the words, click the speaker button.
You can make the words (on average) easier or harder by changing the level. This cannot be done when a game is in progress, but you can pause the game and change the level to get a new grid at a different level.
You can make this a classic game of "find the pairs" by clicking on the eye button to hide the words. You can switch back and forth between visible and invisible words while playing a game.
You can make the word grid larger/smaller by clicking on the grid button.