This means that everything is actually one and multiple at the same time (that is, all are manifestations of many minds and also part of the One Mind or Buddha Mind).
So the idea is that everything is a manifestation of the One Mind, with the same origin, so they share the same nature, and therefore do not interfere with one another.
All things in the world have six aspects = totality, individuality, similarity, difference, integration, disintegration. They are both in union and in difference.
The various parts and the whole do not have inherent nature; their existence, in part or in total, depends on our minds.