The North Pole is the point that is farthest north on the planet Earth. It is the point on which axis of Earth turns. It is in the Arctic Ocean and it's cold there because the sun does not shine there for about half a year. The ocean around the pole is always very cold and it is covered by a thick sheet of ice.
There is a star, called the North Star or Polaris, that is always in the sky above the North Pole. People can tell how far north they are by seeing how high the North Star appears in the sky.