Sweet red beans are used in many desserts and snacks in Korean cuisine. Canned sweet red beans are made from dried red beans (aka azuki beans) and can be found in Korean grocery stores, on Amazon. or make your own at home using the method described in my patbingsu recipe.
My cookbooks
Which to get? my first book has all the recipes for all the essential Korean pastes and sauces, but my second book Maangchi's Big Book of Korean Cooking has more recipes. Both are best sellers and either one is a good choice if you want to learn Korean home cooking.