Illustration of a characteristic three-dimensional flower bed

Quick answer：

A three-dimensional flower bed is a type of garden feature that consists of raised beds made to hold plants and flowers. The term 'characteristic' implies that the design or style of the flower bed is unique or notable in some way. An 'illustration' would be a visual representation of this design, typically used for planning, marketing, or artistic purposes. Such a design might include specific plant arrangements, shapes, or materials that make it stand out among other garden elements.