The Raspberry Pi camera modules come as a small board which is attached using a ribbon cable. Here is a video that shows how to do this:
James demonstrates how to unpack and set up the camera board.
The two Astro Pi units on the ISS each have a different camera module: one has the standard visible spectrum camera (green) and the other has the Pi NoIR camera (black). These are both five megapixel cameras, giving high quality still images and supporting a variety of video recording modes, just like those found in a normal mobile phone. You could program these cameras to record timelapse videos of the Earth spinning below, or even recognise the faces of the crew when they float near the Astro Pi.