Pluto is a small distant planet. It is farthest from the Sun in our system. Pluto completes its revolution in 248 years and so remains about 20 years in each sign, marking an entire era and generation. It symbolizes all that is hidden, buried, and instinctive. It influences the destruction that prepares renewals, death, and rebirth. He is the master of Scorpio and metamorphoses.
A positive transit of Pluto gives power, charisma, and a lot of clarity. But in case of negative transit, it causes anxiety, behavioral problems, and a tendency to destroy. In every case, it is the symbol of an end that precedes a new cycle or a new beginning, a little like a moult that is necessary to continue to grow.
The transits of Pluto on a natal chart last about a year. These are powerful and lasting influences that mark a destiny: life is never quite the same after a passage of Pluto on a sensitive point on our personal map.