It means "no worries"  for the rest of your days!! But first you must kill your uncle before he kills you. Then no worries untill the next badass lion aims to take you out. Idk maybe I'm reading to far into it but the uncle seemed like a normal lion trying to be the alpha and it just didn't work out for him. Ole Simba's heart of gold got him through. But in a pride of lions and lioness there's no room for the good guy lol...