beta is a measure of volatility, and the degree to which a given stock has moved vis-a-vis general market moves. A high beta stock move more than the general market (and inthe same direction).
If you Google something like "investment terms beta" you wil find any number of good glossaries relevant to investments and stock trading.
If I could afford to buy all of them, I would not need to buy any of them and I sure wouldn't be spending time on the message boards!