A kick rocker is the area of boat where it curves up. The kick is the front and the rocker is back of boat. It allows the boat to glide over waves and give riders a good feel.
The bigger the curve the bigger the waves the boat can handle because it pushes the you up over large size waves.
A lesser kick gives watercraft better stability. Not all have a kick.
The term kick rocker usually describes a raft or kayak. The kick keeps the front of boat out of water.