Means something we have yet to understand.
And I am sure we have not even touched the tip of the iceberg.
I tend to use my imagination to help me get to grips with that which many call supernatural, if that makes sense.
A quote from William Shatner:
"I think the supernatural is a catch-all for everything we don't understand about the vast other parts of life that we cannot perceive."
And I think the same.