It means that your soul leaves your body and crosses into the spirit world. You can then visit with other spirits or see things you wouldn't normal be able to see. It is incredibly dangerous as a malicious spirit could take over your body. I have done this a couple times but came out ok. I was able to contact other spirits and I was able to find some closure when an important spirit to me passed over. But it is something I would advise against.
I used to be a practising wiccan. I am very well versed in a number of things to do with what you would call witch craft (though to be honest that is a very negative term for something that is extremely peaceful and harmonic at its core). I still practice some things and keep in regular contact with my spirit animal. A friend of mine who was a powerful witch in her own right when she lived on this planet once told me my soul was very ancient, it was of the earth and that I was probably a shaman in a remote past life. We believed that we had lived a number of lives but I'm not getting into how we knew because that was something very special to us.
Studying mythologies and ancient histories is also a pass time of mine