It indicates the car speed.
See also:
3. Front Fog Light Indicator — If Equipped
This indicator will illuminate when the front fog lights are on. ...
Fan speed adjustment
Proceed as follows:
❒ open completely central vents and side outlets;
❒ turn knob (A) to the blue sector;
❒ slider (B) at ;
❒ turn knob (C) to the required speed;
...