Meanings according to Rider-Waite:
ASTROLOGICAL SIGNIFICANCE: The Moon as a symbol of our "lunar" consciousness, intuition, and the power of our subconscious forces.
THE PRIESTESS. The Priestess personifies our unconscious forces — intuition, premonition, often inexplicable yet utterly firm certainty about something. She is the key to that mysterious truth which eludes the logically thinking mind. She knows that the truth we can express in words is never eternal. Her bright side is the expression of patience, understanding, indulgence, kindness, and the ability to forgive, the use of the powers of the subconscious for the good of people — for the sake of help, healing, clairvoyance. Her shadow side, however, corresponds to the archetype of the "dark sister" who uses her spiritual powers to seduce others, lure them into traps, or otherwise harm them. In the Tarot, however, her bright, kind side is most often emphasized. She is considered one of the three "guardian angels" since, according to Christian mythology, the Holy Virgin can make a person invincible.
From the book: Hajo Banzhaf. THE TAROT HANDBOOK. Translated from the German by E. Kolesov. Publisher: Center for Astrological Research, 1999.
2 — THE POPESS — Moon. The second card of the MAJOR ARCANA is THE POPESS (also known as THE PRIESTESS) or the Female Pope. She is associated with the curious legend of the only woman who ever sat in the papal chair. Pope Joan is supposed to have done this by dressing in men's clothing, and was stoned to death when the deception was discovered. This card depicts a seated woman, crowned with a tiara that emits a lunar radiance. On her lap lies the Torah — or the Book of the Law (usually open), and in her left hand are keys, golden and silver — the secrets to the doctrine. Behind THE POPESS are two pillars with a multicolored veil drawn between them. Her throne stands upon a checkered floor. A figure called Juno (Divine Wisdom) often replaces THE POPESS. Astrologically, the translation of the hidden into the manifest is governed by the Moon, with which this card is correlated. It is that primordial form which the invisible wave assumes in the world, each moment newly embracing the unity of life. Linking the cosmos and humanity, this wave of heavenly will is transmitted through herself by THE PRIESTESS, depicted on the Second ARCANUM of the TAROT. Upon her head are the cow horns of Isis — the characteristic symbol of the Moon. On her lap THE PRIESTESS holds an open book or scroll, in which all that must be has already been inscribed. This ARCANUM is also called "The Gates of the Temple": they admit the cosmic flow onto the Earth and open before the seeker the mysterious path to another existence. With THE PRIESTESS is correlated the inductive mind, connected with the cognition of truth within oneself. This is the intuitively true and singular movement of the soul which justifies the leaving of "home" and the going forth into the world. This going forth may be correlated both with such concepts as "wealth," which the soul finds in the world, and with the "recompense" it receives by opening itself to the flow of higher forces. Identifying with this flow and entering with it into the incarnate world, the soul is drawn into the cycle of fortune and misfortune. THE PRIESTESS, preserving the connection with the higher, symbolizes the immortal maternal principle that does not allow this endless flow of life to be interrupted.
Upright position, the card of THE PRIESTESS symbolizes intuitive penetration into the essence of new decisions and the comprehension of hitherto hidden factors influencing a person and their life (goals, work, hobbies, family). This is also the unconscious influences of your psyche upon those around you and upon circumstances. It is not excluded that you yourself, in some way, unknowably, exert influence upon your surroundings. You are intensely trying to understand the "hidden" meaning of something (an act, an event), and this is fraught with difficulties. And... it is precisely here that you should "in defiance of all deaths" listen to your intuition!
Reversed position, THE PRIESTESS signals problems that are the result of a lack of insight and foresight. This is also superficial knowledge, presumption, and conceit. For a woman — the impossibility of cooperation with those of her own sex; for a man — the rejection of such feminine traits of character as tenderness, gentleness, sentimentality, solicitude. Another meaning of the card is physiological passion. "Knock at the gates of the future and they shall be opened for you. But endeavor most carefully to study the routes of the path along which you intend to pass. Keep silence concerning your intentions, so as not to provoke the opposition of people against them, for sometimes even close friends may turn into your enviers."