On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough description of the side quest Nostalgia.
Rewards: 1,200 XP.
In the place marked on the image above, you will meet a farmer who apparently needs help. When you talk to him, he mistakes you for his child (Rose) and asks you to carry the crates under the shelter next to the house.
Take the crates and move them to the designated area. Be sure to place them in the marked area, not directly under the canopy.
Then sit on a bench and listen to the man's story. After the conversation, the mission will end.