Q: I took the car to the dealership for a oil change and they said the CV Axle (whatever that is) needs to be replaced. how long can I drive

The CV axle is the "driveshaft" for your vehicle, and there are two of them. They are the shafts that connect the transmission to the front wheels, and transfer the power to drive the vehicle. A CV axle can fail in a few different ways, as there are a multiple parts that actually make up a CV axle. There is no way to guess how long you can drive on an axle that has been deemed bad. It depends what parts are bad, the driving conditions, and your driving style, so there is no way to say how long it will last. If a CV axle fails, you will be stranded until the axle is replaced, because when they fail, your transmission cannot get the power to the wheels.