Upright the Seven of Swords is read as strategy, stealth and acting alone, whether through legitimate cunning or through outright deception; reversed, as exposure, confession, or a scheme that has come to light.
This is one of the more morally ambiguous cards in the deck, and readers are divided about how much weight to put on the theft reading specifically. Waite's own text gives quarrelling, a plan that may fail, and an unstable, wavering policy rather than theft as such, and the strong association many modern readers make between this card and literal dishonesty or infidelity is a later, considerably more specific development than his printed meaning supports.
Because the picture withholds a verdict on the figure's motives, careful readers generally treat the card as describing a strategy carried out without full transparency, rather than assuming bad faith outright; the same image supports a reading of a querent quietly protecting their own interests as easily as it supports a reading of a querent taking something that is not theirs, and the surrounding cards usually have to settle which is meant.
Reversed, the confession or exposure reading is fairly consistent across sources, and represents one of the clearer cases in the deck where the reversed meaning genuinely completes the upright one rather than simply opposing it: a strategy pursued in shadow, in this card's logic, eventually meets daylight.