Fleeing units turn around to face away from the victor and then move directly forward a number of inches equal to their Flee roll.
If the fleeing unit rolls higher than the pursuers, or has not been pursued at all, then it has escaped. With a bit of luck, the warriors will come to their senses once the immediate danger has passed, and might yet play a useful part later on in the battle.
To resolve the flee move, turn the unit around about its centre so that it is facing directly away from the enemy unit (ignoring the enemy unit).
The unit then flees straight forward a distance equal to the result of the Flee roll. This is otherwise treated exactly the same as a flee move in the Movement phase. You'll remember that fleeing troops are assumed to run around, force their way through or otherwise avoid other units and impassable terrain in their desperate flight.