Second building you open. Pretty self-explanatory. This is where your Survivors go to eat. Though not its only source, the Cookhouse uses a certain amount of meat from the Hunter's Hut. Keep this in mind in the early game and make sure your Hunter's Hut is producing the maximum amount of meat it can.
This building is a main component in keeping your Survivors healthy and happy. If they aren't getting the proper nutrition, their mood can drop and they will even get sick. This happened to me. Even though I was being good with setting the Furnace to max during the night and storms and my Shelters were all upgraded to their max, my Survivors started getting sick. Took me a minute, but I eventually discovered it was because my food quality was too low.
Luckily, there is a menu you can change to increase the quality of food for your Survivors. When you tap on your Cookhouse, at the bottom you will see a little yellow menu button.