Upright the Three of Wands is read as expansion, foresight and the first returns of an effort already underway; reversed, as delays, obstacles, or a lack of foresight undermining a promising venture.
Older cartomancy read a bare three of wands as strength established following the Two's initial assertion, a settled early success rather than Smith's specific picture of ventures already sent outward and awaited; her ships on the horizon give the card its now-standard association with trade, travel and results not yet fully in hand, a reading the older number-based tradition supports only in general terms.
Waite's own printed meaning, established strength, enterprise, effort, trade, commerce, discovery, is close to the picture and has proven one of the more durable pairings in the deck, surviving into contemporary practice largely without the softening or hardening many other cards in this run have picked up over a century of reinterpretation.
The reversed meaning is comparatively harder to source directly to the picture itself, since nothing about a figure with his back turned obviously signals delay; most current readers derive it instead from the suit's general logic, that fire's forward motion can stall as easily as it can succeed, treating the reversed Three of Wands as this specific, promising launch meeting resistance rather than as any failure inherent to the plan.