A snowman is a classic winter symbol that consists of three stacked snowballs, with the largest on the bottom and the smallest on top. It is typically adorned with various accessories like a carrot for a nose, coal or rocks for eyes and buttons, sticks for arms, and a hat and scarf for added charm. Building a snowman involves rolling the snowballs to create the body, stacking them, and then decorating it to give it a whimsical and festive appearance.