The name of the holes is via stitching, a via fence or a picket fence. It is used to control EMI at very high RF frequencies, such as getting in or getting out, and can also reduce the resistance of the connections at DC.

The holes on the edge are vias. They are connecting that one piece of ground plane to another one on another layer. The reason of using it are various, for increasing current carrying ability, thermal transfer, EMI reduction, and any number of other reasons.

My favorite psot here. Its very impressive and helpful.