The occult reading of this card was assembled in the nineteenth century out of material the fifteenth century did not have. The Golden Dawn gave the second trump the letter Gimel, the Moon, and the thirteenth path of the Tree of Life, the long central path from Kether to Tiphareth that crosses the Abyss. That is a striking and coherent assignment, and it is barely more than a century old.
Waite layers on top of it a set of identifications drawn from his own reading: the pillars of Solomon's Temple, the Shekinah, Isis, and the scroll of a hidden law. Crowley extends the same line into the Priestess as the highest and least approachable of the feminine figures in the deck. What all of these share is an idea of the card as knowledge that is present but withheld, and it is that idea, rather than any medieval one, that most readers today are actually working with.
The reading range is correspondingly narrow and unusually consistent. The card is taken for intuition, latent or unspoken knowledge, patience with what has not yet been said, and the correctness of not forcing an answer. Where readers differ is in tone: some read it as an instruction to trust an inner sense, others more coolly as a statement that the information required is simply not yet available and no amount of interpretive effort will produce it.
Reversed, Waite-derived practice reads secrecy turned unhealthy, self-deception, or knowledge withheld to control. Readers who do not use reversals reach much the same territory by noting which cards fall beside her.