If you climb the tower and bring Korin an offering, he will train you and you will be able to create your own special moves.
If you prove yourself to be an extraordinary student, Korin will let you sip the Sacred Water, un-locking your true potential.
The tower was built to honor a great hero (it is never stated who the hero is nor is it known if he was the same being as Korin, but in anime filler it is implied that this hero could have been Olibu). The "Owner", Korin, grows Senzu Beans in the tower, which he gives to the Z Fighters freely whenever he has some in stock, most often via Yajirobe. However, the Japanese version of the movie Dragon Ball Z: Cooler's Revenge implies that Korin can only allow the Z Fighters to gain the Senzu beans if they climb all the way up, and if they only climbed up halfway, he declines the request. In the dubbed version, it is known as the Holy Tower or Korin's Tower; while in the Spanish and Portuguese dubs as Torre Karin (Karin Tower).
A hole in the top of this tower fits Goku's Power Pole, which serves as the link between the tower and Kami's Lookout. It should be pointed out that it is made of a quite durable material, that the structure itself is so hard to destroy that Mercenary Tao (Tao Pai Pai) had trouble cracking one of the columns.