Jupiter, the first of the so-called "slow" planets, opens the ball for the traits of a generation. Indeed, it takes one year to cross a sign and, therefore, gives characteristics common to all people born that year. Jupiter tells us about our mentality, lifestyle, and how each of us flourishes.
The transits of Jupiter are never evil. At worst, Jupiter encourages excess such as greed, unnecessary expenses, hyperactivity, constant chatter, or dramatized emotions. When the transit is positive, Jupiter brings luck and personal fulfillment. It is a formidable engine of evolution, and its conjunction with the natal Sun generally indicates a tremendous leap in the quality of someone's life. Conjunction transits occur every 12 years, so it's worth staying tuned for a chance. The transits of Jupiter usually lasts 2 or 3 weeks, but in the case of retrograde, the effects are much longer, and the results more durable.
For each of the 12 astrological signs, here is the meaning of Jupiter's position in each sign.