|Zen rock gardening (bizarrocomics.com)|
"Zen" is a way of saying "fully collected attention, fully absorbed mind," a natural state sometimes referred to beginner's mind.
It is confounding the Tao, "going with the flow," the way, the yin and yang of cyclical existence -- in Taoism as if it were Buddhism. Taoism so mixed with Buddhism, each influencing each other and mixing like water and milk, that it is not far from some aspects of the Dharma. But they are not actually the same at the core, just as cultural interpretations.
It means to cultivate something, to develop something, to bring something into being (bhavana). One brings virtue, concentration, and insight into being with balanced effort.
It is part of Japan's artistic tradition turning the mundane and sparse into reflections of art and order.