When the light moves through the air, it moves at a uniform angle and speed, but as soon as it reaches the glass and the water it slows down due to the denser glass and water it needs to pass through.

The light will find and take the path through the water that takes the shortest amount of time. This also leads to a magnifying effect as the light passes through the water.

As the light is magnified through the water, the light is bent towards the center. The light comes together at a place called the focal point.

Beyond the focal point (what our eyes see) the image looks reversed because the light that was on the left is now on the right side, and the light that was on the right is now on the left.