To get this achievement you need to have completed 1 FULL game in 2 different languages.
You just need to change a language in the Help/Options menu. This will reload the wordament game. Start a game and try and find a word. Once you have found one let the game play until the end.
You then need to do exactly the same in another language and the achievement will pop at the end of that game.
Note: If you join a game that has already started, you will have to wait until the next game to unlock this achievement. They both need to be full 2 minute games and you most get a word in both games!