It means that from now on, you will have no worries. Hakuna Matata can be said to be the most famous slogan among the lion kings, and it is also Timon Pumbaa's philosophy of life.

After they saved Simba, they taught him the philosophy of Hack's Na Matata, forgetting the troubles, the episode in the second half of the song,

It means that Simba wants to be satisfied with the process of growing from a child to an adult.