What does the arrow symbol do?

I'm not sure if it shows up in the mobile versions, but on the Facebook version of WWF, I sometimes have a strange arrow symbol appear on the tiles. I can move it around by clicking on different tiles, and if I click on the arrow symbol itself, it alternates between pointing down and pointing right. It never seems to point left or up.

Where does it come from? What does it do? Sometimes it covers up tiles that I would like to see, which can be a pain. Is there a way to get rid of it?

If you turn the keyboard function off the arrow does not appear. Do this by clicking on the three horizontal lines at the lower left of the board. In the pop-up, one of the selections is "Keyboard Input". Clicking on it will toggle it on or off. When it is off, that annoying arrow disappears. Click elsewhere on the screen to get rid of the pop-up.

Figured it out! Left clicking anywhere on the board will place the arrow. Then, instead of clicking and dragging letter tiles onto the board, you can type the letters on your keyboard. The direction that the arrow is facing is the direction that the letters will be placed.

There doesn't seem to be a way to get rid of the arrow icon apart from refreshing the browser or reloading the game.