Upright the Queen of Cups is read as compassion, intuition and emotional depth offered with steadiness rather than volatility; reversed, as emotional overwhelm, a caretaking that has tipped into self-erasure, or feeling that has flooded past the boundaries that made it safe to trust in the first place.
As a person card, she is one of the four court figures most often used to represent a specific querent or a specific third party in a reading, conventionally read as an emotionally perceptive person whose empathy is trusted precisely because it does not overwhelm the people around her the way the suit's more turbulent cards can. This distinguishes her from the Knight of Cups, whose feeling is expressed outward and in motion, and from the King of Cups, whose feeling is mastered through control rather than through depth as such.
The reversed reading, emotional flooding or boundary loss, is a comparatively modern gloss; Waite's own printed meanings for the reversed card run to a colder, more transactional sense, a false or dishonest person of some ability, which most current practice has quietly replaced with a psychological reading closer to the queen's own emotional register than to his character judgment.
Because the court cards are frequently read as people, the Queen of Cups is also commonly used diagnostically, as an invitation to ask whether the querent is currently offering the steady, contained empathy she represents, or whether that capacity is presently running low.