Megan, "cardio" refers to exercises that get your heartrate up. Anything that would give you a vigorous work out. It's important to do it for at least 20 minutes.
Keep up the good work, by the way. It's good to exercise. I've been doing a lot more of it too, for my cardio I usually jump rope for about 30 minutes.

Thanks for the clarification, Fryl. I do some jogging in place. I guess that counts as cardio.