The amount of a sculpt produced during the casting process.
Most producers of statues and busts determine some sort of set edition size to give their statue a collectible edge.
A low Edition Size can increase collectibility and increase demand. Conversely, a high Edition Size can sometimes reduce the aftermarket price of a statue drastically.
There is a difference between the common ideas of "Limited Edition" and "Numbered Edition." Some companies will produce a "Limited Edition" wherein the sculpt is labeled as "1 of xxxx." It simply means that this is one of a total of xxxx produced sculpts, but is not a specified number. This is seen on many early statues and more casual, gift-store type statues. A "Numbered Edition" implies that each of the xxxx produced pieces in a casting run will be given it's own unique number out of the total, for instance "36 of 3500." These numbers are usually handwritten on the bottom of the pieces by the factory workers.
Occasionally, extremely low or high numbers in a run will be more in demand. Most pieces are not numbered in the order in which they were cast, so obtaining a low number is often little more than a collector's preference.
Some companies also use AP in place of a number.