On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough for the Pig of Prophecy side quest.
Rewards: 1,200 XP.
In the place marked in the image above, you will meet a man who is talking to a pig. The man standing next to him claims that the animal predicts the future.
To get the answers from the pig, one must first drink. Walk up to the bucket with alcohol, take a drink, and then talk to the pig. To hear the rest of the prophecy you will have to drink again and speak to the pig again. The mission will end after listening to the entire prophecy.