Meanings according to Rider-Waite:
ASTROLOGICAL SIGNIFICANCE: Neptune/Jupiter in some harmonious aspect to the Sun as a gift of complete self-realisation.
ACE OF CUPS The Ace of Cups is one of the very best cards in the Tarot deck. Like the other Aces, it points to the greatest opportunity opening before us; this may also be the chance for complete self-realisation. What this means for each particular person depends on their own expectations. The spectrum of meanings of this card includes joy, gratitude, contentment, success, happiness and unity. In first place, of course, stands love as the greatest gift in all its manifestations: love for one's neighbour, for one's parents, sensual-erotic love, love for oneself and love for God. But it may also manifest on the most ordinary, everyday level — as luck, good fortune, a gift of fate, though as a rule without any material substrate: for material "gifts" the Ace of Pentacles is rather responsible. In any case, it must be clear to us that the Ace of Cups denotes some unusually fortunate chance opening before us or before the matter we have set out to undertake; but this chance does not realise itself on its own — for that, effort must be applied.
From the book: Hajo Banzhaf. THE TAROT HANDBOOK. Translated from the German by E. Kolesov. Publisher: Centre for Astrological Research, 1999.
ACE OF CUPS Astrological equivalents: Venus, the Moon, Neptune, Taurus, Leo, Libra, the Second and Fifth Houses. The ACE OF CUPS symbolises a going beyond the world of things. This card, as it were, breaks open the everyday. This, of course, is at its highest manifestation; at the lowest the ACE OF CUPS pleasantly diversifies our daily life. CUPS is a Venusian suit, and therefore everything connected with it brings joy and comfort either to the soul (the higher level) or to the body. The card usually signifies a renewal of feelings; it may appear in a reading for people in whose horoscope Venus returns to its natal place, which happens once every eight years. Of course, the ACE OF CUPS arises in any reading, but it plays itself out most vividly precisely in this "Venus return" key. If you are in a state of agonising discord with the world, the ACE OF CUPS may signal the beginning of reconciliation, of harmonisation. It may also serve as a hieroglyph of your "okay-ness". The ACE OF CUPS is a joyful, major-key card. The pitfall: actions conditioned only by feeling; the danger of being buried under emotions.
UPRIGHT POSITION In the upright position the card usually indicates that you stand on the threshold of something that will bring you joy, peace and harmony. It may signal the beginning of a great feeling, some event that will entail a romance, possibly the conclusion of a marriage. Apart from Venus, the Moon and Neptune sound distinctly in the theme of the ACE OF CUPS. This card, when located at the nodal points of a spread, may indicate a sharply heightened intuition. In such a case one should not neglect one's sensations, presentiments, illuminations, dreams. The card may also mean: readiness to be filled, the ability to accept what is given, joy, happiness, fecundity, productivity, generosity, perception of the world in a rosy light. In old manuals the ACE OF CUPS was associated with such concepts as feasting, the receiving of guests.
REVERSED POSITION In the reversed position the card points to emotional stagnation, an absence of emotions, even to "sensory deprivation" (emotional hunger). It may mean: change, destruction, instability, barrenness, unrequited love, clouded joy, false feeling, inconstancy.