Refraction is the bending of light or sound as it passes through something like a wall (sound) or a window (light).
The result of the refraction of light particles as they pass through water or a prism is a rainbow. Since different colored light particles move at different speeds, refraction causes the colors to split by how fast they are moving. Sound waves also experience refraction when traveling in warm air over cool water. This is why you can sometimes hear someone talking from far across a lake in the morning or evening.
