Typically a bonding wire connects between multiple grounding rods.
The motor is already mechanically attached to the dish, but an additional wire can bond the motor ground terminal to the pole or directly to a dish grounding rod. Most installers would attach a ground wire between the pole and structure ground. If the dish was located a considerable distance from the structure (or if installing in a high lightning activity region) a ground rod (or several ground rods) would also be installed at the dish, and bonded to the structure ground.