A basic knowledge of sporting events is helpful to have. I would brush up on basketball, soccer, volleyball, softball and baseball. For softball and baseball, it's good to know the positions, as the director may say "Camera Two, frame up the Right Fielder." For other sports, you're usually just following the action.
I would brush up on your camera basics too:
Aperture: knowing what an F-stop is, how to change it, and how it effects the image.
Color Temperature: knowing what Kelvin is, how to change your color temp and how it effects the image.
Gain: knowing how adding or subtracting gain effects the image (brighter vs. darker) and where on the camera that function is done.
Experience setting up a tripod is helpful too. Overall, the ideal Camera Operator is easy to work with, takes direction well and is a team player.