I have a 2001 Ford Expedition, my question is when I break you I feel real hard vibration what needs to be done?

It is highly likely that the pulsation and vibration that you feel under braking is a warped rotor. Front brakes are used more in a vehicle due to the weight transfer under braking. I would start with replacing the front rotors. They are relatively inexpensive, and also replace the pads.

Warping mainly occurs when the brake rotor overheats due to excessive braking. The overheated metal in the rotor will begin to cool more rapidly in different areas which will cause the rotor to "warp".