This volatility measure is supposed to give you some sense of how far the fund will fall if the market takes a dive and how high the fund will rise if the bull starts to climb. A fund with a beta greater than 1 is considered more volatile than the market; less than 1 means less volatile.
So say your fund gets a beta of 1.15 -- it has a history of fluctuating 15% more than the S&P. If the market is up, the fund should outperform by 15%. If the market heads lower, the fund should fall by 15% more.
Problem: For funds that don't correlate well to the S&P, beta just doesn't tell you much.