Meanings according to Rider-Waite:
ASTROLOGICAL SIGNIFICANCE: The Sun in the 5th house as a symbol of the joy of life, creative potential, and the enjoyment of play.
THE SUN The Sun card expresses love of life, joy of living, warmth, and confidence in the future. In our consciousness it corresponds to the forces that help us to attain clarity, overcome apprehensions and deep-seated fears, and surmount delusions. Furthermore, the Sun personifies youth and such a freshness of feeling as though one had been born anew. This is the bright, sunny side of life. On a deeper level, it is advice to overcome one's dark side, to allow our solar nature to unfold, to recognize within ourselves our "shadow Self" and to bring it forth into God's light.
From the book: Hajo Banzhaf. TAROT SELF-INSTRUCTOR. Translated from the German by E. Kolesov. Publisher: Center for Astrological Research, 1999.
19 - THE SUN The Sun The nineteenth card of the MAJOR ARCANA is called THE SUN. Depicted upon it is a boy, or a boy and a girl, standing in a garden within a magical circle of flowers. Behind them is a stone wall, above which the Sun shines. The children symbolize Faith and Reason, which must exist as long as the Universe exists. The Nineteenth arcanum of the TAROT depicts the Sun, the children, and the zodiacal circle, whose base is the sign of Cancer (the sign of birth) and whose summit is Capricorn (the sign of attaining the result). The card portrays the immediate joy of life. Depicted upon it are playing children, whose spiritual activity many times surpasses that of adults. This cinarot combines within itself the characteristics of such planets as Mercury and the Moon — the two planets of the most "childlike," direct perception of life. THE SUN is the path to the light, to clarity, the fullness of strength, the affirmation of life, and illumination. This is the energy that opposes those influences of the collective field which give a person doubts as to the correctness of his actions, since a person, from a collective standpoint, is not always able to evaluate himself and his place under the Sun. If the PRIESTESS and the MOON are the feminine road to wisdom, then the MAGUS and the SUN are the masculine path. THE SUN is the striving toward the light, the reconciliation with one's "shadow" side (that which has been brought forth into the bright light of reason, formerly unconscious, frightens no more). This is the Sun as the source of life — generous, purifying, giving. It is the realization of the highest within oneself, vitality, warmth, freshness. But... it is also self-satisfaction, and the mania of greatness, and the cult of personality, which begins when the generous deity of the Sun is replaced by a human being (the Absolute is replaced by a complex of qualities, as a rule, contradictory).
Upright position the card symbolizes happiness, material well-being, good health, great successes, achievements in any field of activity, resourcefulness, inventiveness, the respect of those around one — in a word, the blossoming of life. Sometimes THE SUN may signify a celebration over the attainment of something important — a triumph, a reward, optimism, a good future, as well as the long-awaited fulfillment of wishes: the birth of a child or joy over the successes of children.
Reversed position the card symbolizes difficulties in contacts with people, problems in marriage and in partnership, misunderstandings, false notions about success, excessive bustling, activity that yields no results. Sometimes the reversed position foretells problems with health, family troubles, or a temporary separation from a loved one. Not being a bad card in the strict sense, the reversed Nineteenth ARCANUM means that all of the positive influence of THE SUN in this position is weakened: success, but only after considerable effort; hopes and dreams concerning matters of the heart will come to pass, but not fully. And yet THE SUN represents new perspectives of being that have opened before a person after sleep (the card of the MOON), when he has the desire and the strength to engage directly in the spiritual life of the world in all its fullness. THE SUN is the finest card of the ARCANA.
"You have attained a high level of consciousness. You have a rich, wise soul, and you know now what happiness is. You have understood wherein lies your destiny, you have settled your karmic debt, and you can now help others in this also." Papus