Whilst often seen as a place for beginners, the ability to climb slabs efficiency can help more than just novice climbers improve their climbing efficiency. A slab is generally any angle of climbing surface where the climber can get all their weight off their hands and onto the feet. This generally equates to anything from few degrees off vertical through to some much more easy angle slabs.
At its most simple slab climbing comes down to rocking your weight from one foot to the other. This technique is generally called a rock-over. This transfer of balance from one foot to the other is also the fundamentals of nearly all climbing movement.