To make food, you need to purchase the upgrade for your phone from the ABD in Resident's Services and unlock the cooking mechanic. Once you've cooked a meal, you can either use it as decoration for your house or island, send it to a friend, give it to a villager, sell for Bells, or eat it yourself. Eating a cooked dish will, like eating fruit or candy, give you the power to break rocks or dig up trees for a specific amount of time. The more precious the food, the higher the bells you get from selling it. For example, selling Tomato curry food, you can get 2,520 Bells. When you make food successfully, you don't have to worry about the food going bad, it will never rot. To have food right away, you can choose to Buy Animal Crossing Food directly here.