What is a circuit?
Circuit training is a training method that involves performing a set of pre-programmed exercises one after another. It's also known as interval training. There are a few seconds of rest between exercises, but people who train regularly won't need this recovery time other than to move to the next workout station. Once you've finished the circuit, you go back to the start and repeat the whole sequence. You'll do between two and twenty of each circuit depending on how long it takes to perform the circuit, how fit you are and how long the workout is.
The important thing is to adapt each set of exercises on the basis of your own endurance, resistance and strength.