Bonsai literally means “tray planting”. It is the art of recreating a realistic picture of nature in miniaturized form. From the perspective of a site-creator, they are seeding and pruning a
jekyll-bonsai in a small tray-like space. The finer details are described well by the wikipedia article on bonsai:
Purposes of bonsai are primarily contemplation for the viewer, and the pleasant exercise of effort and ingenuity for the grower. By contrast with other plant cultivation practices, bonsai is not intended for production of food or for medicine. Instead, bonsai practice focuses on long-term cultivation and shaping of one or more small trees growing in a container.”
A bonsai is created beginning with a specimen of source material. This may be a cutting, seedling, or small tree of a species suitable for bonsai development.
Bonsai uses cultivation techniques like pruning, root reduction, potting, defoliation, and grafting to produce small trees that mimic the shape and style of mature, full-size trees.
The various steps of the process are still under experimentation and being discovered, but you can learn more by reading about about the plant types that grow in this garden.
And because of the wonders of technology, this bonsai can be displayed for visitors. From their perspective, the creation is experienced as a digital garden which they may traverse at their leisure.