The main meaning is that the world is empty and everything in the world is an empty word. If the heart is empty, there is no need to resist the temptation from the outside world. Everything passes by the heart without leaving a trace. This is a very high realm of Zen, and those who appreciate this realm are called enlightenment.
Bodhi trees have no trees, and the mirror platform is not a platform.
It is nothing, no matter what it is, where will there be any dust?