BRB update 1.3 :
The rules for reinforcements say that when a unit is set up on
the battlefield as reinforcements, it cannot move or Advance
further that turn, but can otherwise act normally (shoot,
charge, etc.).
Q: Can such a unit make a charge move? Can it pile in
and consolidate?
A: Yes to both questions – the unit can declare a charge
and make a charge move, and if it is chosen to fight, it
can pile in and consolidate.
This is what
GW means when they say a unit "can otherwise act normally".