I'm stuck also. I think Dreamwoven provides one interpretation of what that means.
George Berkeley's philosophy claims there is something out there but we cannot experience "senseless Matter". So whatever is out there, it is not senseless Matter. Here's a quote:
To me, I say, it is evident that the being of a spirit infinitely wise, good, and powerful is abundantly sufficient to explain all the appearances of nature. But, as for inert, senseless Matter, nothing that I perceive has any the least connexion with it, or leads to the thoughts of it. And I would fain see any one explain any the meanest phenomenon in nature by it, or show any manner of reason, though in the lowest rank of probability, that he can have for its existence, or even make any tolerable sense or meaning of that supposition. For, as to its being an occasion, we have, I think, evidently shown that with regard to us it is no occasion. It remains therefore that it must be, if at all, the occasion to God of exciting ideas in us; and what this amounts to we have just now seen.
Berkeley, George (2012-05-12). A Treatise Concerning the Principles of Human Knowledge (Kindle Locations 809-815). . Kindle Edition.
It was only recently, after considering quantum physics' "consciousness causes collapse" interpretation, that I thought he might be right. There is something out there. It is not just an illusion inside my head although my experience of it is filtered through my senses, but it is not what we normally think of as "matter".
Here is an InspiringPhilosophy YouTube video attempting to describe idealism based on quantum physics: https://www.youtube.com/watch?v=4C5pq7W5yRM It goes a little fast. Although both Berkeley and InspiringPhilosophy are viewing this from a Christian perspective, I think the conclusions would be the same for any panentheistic viewpoint.
Although I think I get this intellectually and I can even accept that an atom is mostly empty space and that we don't actually touch the floor we walk on but only respond to electromagnetic waves keeping us from falling through the floor like a neutrino would, the idea that there isn't anything there still puzzles me.