Earth is the only planet in the solar system that is known to have life on it. None of the other planets in the solar system have life on them. Earth's uniqueness (in this regard) is due to a fortunate mix of factors. Earth is at the right distance from Sun. If Earth was a little closer to the Sun, it would trap a lot of heat and would be too hot for survival of life. If it was slightly away from Sun, it would have been very cold for life. It also has an atmosphere that regulates the temperature, by absorbing and releasing heat. Earth is also fortunate to have water on it. Most common life forms are aerobic and we are fortunate to have oxygen in our atmosphere.
There could possibly be a large number of other planets, outside our solar system, that may fulfill such criteria. However, we are yet to find life on any other planet.
Hope this helps.