Depending on which side of the spectrum you are sitting, it means:
Car salesman: Power windows and a CD player
Buyer: All the optional equipment that a model can have.
Salesman: This car is fully equipped!
Buyer: So it has a remote starter?
Buyer: 8 speakers radio?
Buyer: Alloy wheels?
Buyer: What equipment does it have?
Salesman: It's fully equipped. It has a CD player and power windows.