It’s a cordless hand drill / impact-drill powered by a 21 V lithium-ion battery pack.
The “brushless” descriptor refers to its motor type: instead of a traditional brushed motor (with carbon brushes), it uses a brushless DC motor — which generally means more efficient power use, less heat, less friction, lower maintenance, and longer lifespan.
It typically includes a 2-speed gearbox (low speed + high speed) allowing the user to choose between torque-focused or speed-focused operation.
Many variants also have “impact/hammer” mode in addition to regular drilling and screw-driving — which gives them extra “bite,” enabling drilling into masonry, brick, or concrete (within limits) rather than just wood or metal.