On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough for the Paola's Dream side quest.
Rewards: 1,200 XP.
In the place marked in the image above, you will meet a man named Jason. A man will show off the majestic structure which he calls home of dreams, built with his wife, Paola.
The task is very simple - just listen to what the man has to say. After a short cut-scene, the mission will end.