Power is a measure of a engine’s ability to do work. Horsepower is an imperial measure of power (as inches are an imperial measure of length).
Power may be measured at the crank, but is typically measured at the wheels using a dyno?. Crank horsepower can be extrapolated from wheel horsepower by guesstimating drivetrain losses, but this is generally not useful because dynos themselves vary, and multiplying by another variable just makes the resulting numbers even less meaningful.
More is better.
See also torque.
