Dream Land is the universe in which the Kirby (series) takes place.
In Gradient Hue, Dreamland appears as a Tier 3 world. However, it is not a battle-focused world. Instead, Kirby is having trouble with various tasks and Gradient wants to help. For example, Kirby will be having trouble crossing a chasm, so Gradient has to hit blocks with Bladion to make them fall and fill in the chasm. Completing this world lets you play Strange New World rather than giving you a Halfcharm.