The "bid size" and "ask size" will tell you how many shares are behind the bid and ask price. The size is typically measured in lots of 100 shares. For example, if the asking price is $9, and the ask size is 15, then that means there are currently 1,500 shares available to buy for $9. These numbers constantly change as new orders come in and get filled, so the lot size does not necessarily guarantee all of those shares at that price.