In POP you are initiated into the feminine current. POP is the first Aethyr with a strong sexual content. Similarly, the next Aethyr, ZEN, contains an initiation into the masculine current. Generally speaking, a male will have a strong sexual encounter in POP but not in ZEN, while a female will have a sexual experience in ZEN but not in POP. The experiences themselves will, of course, be highly personal and no two are likely to be identical.
The Guide in POP is known as the Priestess of the Silver Star. The priestess here is the goddess Isis in her role as feminine initiator. The encounter here is the first half of the energy designed to raise your consciousness beyond the confines of the human mind. It is often sexual in nature because sexual current is quite potent and alluring when used properly. Even females will feel the alluring sexual quality of this Aethyr to some degree. Isis personifies spiritual impulse in its feminine configuration. She will appear extremely lovely and alluring. She is often called the "arch-harlot," always ready to seduce and to intoxicate those who lusts after her.
Now keep in mind that what you see and do here is more figurative and symbolic rather than literal. Isis is a psychic thought-form, not a physical woman. Isis is a representation of the divine feminine self within you. She comes to you in the most desirable form possible to attract you upward toward that which you seek: union with divinity.
After a successful initiation here, you will die unto yourself and a new self will begin to emerge. The divine current changes you and you will never be the same. Going back is not an option any longer, for you will be forever seeking that bliss and union that only occurs when you unite with God. Your road on the quest to your spiritual evolution is now set. Take hold of the reins and proceed.
* additional source material: "Enochian Magick" by Gerald J. Schueler, "The Golden Dawn" by Israel Regardie