The benefits of using a Bosch cordless screwdriver are manifold. Before I mention specific benefits, let's discuss specifically what a cordless screwdriver is.

Basically, there are three different categories of tools used to drive fasteners. A 'fastener' in this article is basically a screw. 

The three categories are hand screwdriver, corded screwdriver, and cordless screwdriver. The hand screwdriver features a handle and a shaft. The end of the shaft will be a variety of heads for different fasteners.
 
The idea behind the screwdriver is to give you a handle that allows you to twist in one direction and rotate a fastener in order to sink the fastener into the material. You twist in the other direction to 'unscrew' or remove the fastener.

The thickness of the handle gives you a better grip and more leverage. Often though, the leverage is not enough and you still cannot turn the fastener. 

This is where a corded screwdriver comes into play. It plugs into an outlet that powers a motor in the driver/drill. 

You get much more driving power and simply pull a trigger in order to rotate the motor. These drivers usually have a 'reverse' as well that facilitates removing fasteners. 

Although very beneficial in many circumstances, a small inconvenience of the corded drill/driver is that you must operate within reach of a powered electrical outlet. That is often not available, or you may also find yourself constant unplugging, moving, plugging in again. 

The Bosch cordless screwdriver overcomes this inconvenience by having a battery supply the needed electrical power to the motor. 

You simply pull a trigger and the Bosch cordless screwdriver rotates the 'bit'. This bit is inserted in the fastener and rotates the fastener, either turning it into the material, or rotating it out of the material.