For some of us... we might go and toke up with spirits after we leave our physical bodies behind when we die.
It's just your spirit leaving the physical shell behind. That way it can go into the next stage of existance. Then the spirit may be able to prepare itself for the next body that it may enter; before the body of the boy, or girl comes out of his, or her mother's womb.
The spirit may do other things way before its time to experience another human life, or "learn" things here on earth.