Beta is a measure of the volatility or of a security in comparison to the market as a whole.
Beta = 1 indicates that the security's price moves with the overall market.
Beta < 1 means that the security is theoretically less volatile than the market.
Beta > 1 indicates that the security's price is theoretically more volatile than the market.
For example, if INFOSYS beta is 1.2, it's theoretically 20% more volatile than the benchmark Nifty. In other words if nifty moves 1%,the stock has the tendency to move 1.2% on that day.