Playgrounds contain bite-size examples of AudioKit and serve as tutorials for many of AudioKit's core concepts and capabilities.
The playgrounds come in two flavors, playgrounds for the iPad Pro's "Playgrounds" application and playgrounds for use inside of Xcode on macOS.
The Xcode playgrounds are more powerful than the iPad playgrounds, and cover more of the various capabilities of AudioKit. But, for beginners the iPad playgrounds might be more fun, especially for kids.