Legend has it that in the Shaolin Temple there was a tunnel filled with 108 wooden dummies in order for the monks to complete their training they had to pass through this tunnel. Each one of these dummies performed a certain technique, which the "graduate" monks had to neutralize on their way out of the temple.
When the Shaolin Temple was destroyed, there were no recorded deaths and no life insurance to prove such accounts, so history blanked itself. The complete history of the shaolin temple cannot be narrated nor explained in detail, thus the vague historical documentation of shaolin archives and chronicles. Only certain and distinct characters like a few are remembered to this day like Ng Mui, the creator of Wing Chun Kung Fu, who escaped and incorporated a training set using a single Wooden Dummy into her new fighting style.
You can practice and develop all of the Wing Chun techniques on the wooden dummy as well as working on your footwork in order to understand the correct distances at which each technique is most effective.
There are basically two kinds of wooden dummy: fixed and floating. The floating one is preferable as this enables you to strike it and have the dummy "give" so that it does not transfer all of the rebound energy back into your striking arm/leg.