The salute is a very old form of greeting. Long ago when people greeted each other, they help up their right hand with the palm forward to show that they had no weapon in it. The salute is also a sign of respect and friendship for a leader or another Cub or Scout.
When you salute a leader or another Cub, you use a special sign. You hold your right hand to your forehead with two fingers spread out to look like the pointed ears of a wolf.
(Extract from "Cub Book" - page 31 - By Scouts Canada)