What is a superset?

Performing alternating exercises for opposing muscle groups.

A1 - Pull-up: 3 sets x 10 repetitions

A2 - Front squat: 3 sets x 8 repetitions

Here you would do one set of pull-ups for ten repetitions and take a break. Then do one set of front squats for eight repetitions and take a break. Now, you've completed one superset. You would repeat this alternatively until all three sets are done.