Andra asks you to gather 5 Oran Berries for him, since they are good for distracting wild pokémon.
The Request
Talk to Andra near the Front Gate of Jubilife Village to accept the request.
Gather Berries
You can obtain Oran Berries by throwing a partner pokémon at a berry tree. Oran Berries are blue, so look for trees that have blue berries in them.
Completing the Request
When you have at least 5 Oran Berries, talk to Andra again to give him the berries. You will get 3 Revives.