The Status bar provides information about the current state of Align Tool. It will appear while you are in interactive mode, and will update its information whenever you change something relevant, whether by clicking in the User Interface or by using the shortcuts.
The Status bar informs about the three main concepts of an alignment: Direction, Plane and Origin.
The Status bar replaces the default header of tools in the 3D view until you confirm the alignment or exit the interactive mode. To toggle its visibility, just use the shortcut (H).
