Candyland is a setting, often found in children's media, where the world, including buildings, the natural environment, and sometimes even people, are made of sweets. For example, the clouds are made of cotton candy, the buildings from gingerbread, etc.

This land is used to express whimsy. Artists use their imaginations to imagine how miniature, colorful candies can construct a large environment that replaces common images such as trees.

Note that this is called "Level Ate" on TVTropes , where you can find examples.