A smoothed current means that the current leaving the box and being sent to the clearomizer or atomizer has a strictly constant (and not jerky) voltage between the moment you press the power button on your e-cigarette and the moment you release it. The result is a smoother, rounder vape.
There is an electronic system in the boxes to transform the power of the battery or accumulator to the value you have set, so the output current from the electronics is not necessarily flat or smooth.
