The Farmer mentioned that a Yak would be useful to produce wool. The wool could be used to craft warmer padding kits and armor that protect against the biting winds. To tame a Yak, you must first craft food baits. Craft or obtain at least 3 Yak baits to continue.

Now that you've procured some Yak food bait, you have to search for a Yak! There is a spot marked on your map where Yaks can be found, but anywhere is possible. The quest will only update to the next page when you reach the designated area, but you can complete the quest by taming any Yak.

You've reached the designated spot for taming a Yak. Now tame a Yak with the food bait by carefully approaching, feeding, and petting it. Once the Yak is comfortable, it can be picked up and brought home for wool!