Mention bees and most people think of the 'social bees' - swarms of honey bees, or gangs of bumblebees. In fact, the vast majority of bees are solitary, living out their lives as single bees, provisioning single nest cells, rather than working with many other bees to raise huge numbers of offspring in shared nests.
And fear not! Mason bees can sting, but only the females and then only very feebly. They will only attempt to sting you if roughly handled. Solitary bees live solitary life-styles, so they do not gang up on you in terrifying numbers. In fact they don't gang up on you at all. They hardly bother to defend their own nests! In short, they are virtually harmless.