Often, when we're selling options, we want to sell options on stocks that have a low Beta. Stocks with low Beta tend to move in magnitude about equal to or less than the magnitude of the overall market. So if you have a stock with a Beta of 1, then it is expected to move with roughly the same magnitude as SPY.
Beta is not directional so if SPY goes up 1%, then it would be expected that a stock with a Beta of 1 would also move roughly 1% (up or down).
These are great for options sellers because their moves are more predictable. The option income will usuall be lower as a result.