Ah yes, it's essentially tool tip for a forward button, which works just like in your web browser.
The english description I made: Go to an edit you loaded in the past but moved back from
Forward button only works when you hit "back" button (just like in a web browser). You can move in history, back and forth, but you can't move forward, if you didn't go back in first place. It's important not to confuse this with Huggle's "next" button. Forward will not move you forward in edit queue, just within history.