This is testing shutterspeed, with a low ISO.
Here is my friend CC helping me with different ISO settings. ISO is the measure of a photograph's film sensitivity to light. On this picture, we used a higher ISO. As you can tell, the picture came out brighter.
Here, we used a lower ISO. The picture as you can tell is darker than the first.
In this picture below, I used an even lower ISO. You can tell as the whit walls are now yellow, and the space looks dreary.