Viviane,
There are accepted rules that scholars and experts in the fields of Bible/book research use to determine which parts are symbolic, which are poetic, which are apocalyptic, which are narrative/prose, which are songs, etc.
There is nothing magical or mystical about it. I never say anything without checking it against the scholars and experts and their accepted rules of exegesis and interpretation.
Now, as far as what "spirit" is, the Bible simply defines it as unseen forces/beings which have a different "body" than humans do. Anything beyond that knowledge is a mystery.
The book of Revelation tells us it is a book of "symbols" or "signs," so we know it's symbolic for sure.
Bible scholars are pretty much in agreement that "wearing a crown" or "sitting on a throne" are phrases that mean "king" or "ruler."
This isn't rocket science or magic here.