The earth was transformed into the "ultimate training ground" by Beerus, the powerful god of destruction in the universe. The purpose is to screen out the strong ones who can fight with him through the extreme environment.
After Lin Ye was defeated by the God of Destruction in the "last round of trials", he was given a chance to be reborn because the angel believed that his "potential was up to par". He retained his memory but lost his power, and was simultaneously bound to the Dragon Ball system.
See how the protagonist uses Saiyan blood to grow step by step and fight against the God of Destruction again.
