A superset is a combination of two or three moves where the exercises are done back to back with no rest in between. For example, if you're doing Front Lateral Raises then move on to next exercise Side Lateral Raise you do so without taking any rest periods. Between supersets you rest only long enough to recover and catch your breath, then hit it again.
A drop set is basically an extended set of a move, usually performed as the last set of that exercise as a burnout. You start off with a higher weight like 35 pounds and then you drop the weight to 25 pounds and so on as instructed in the app and do as many reps as you can. Like supersets, there are no rest periods between weight drops. You will just have time to switch the weight to a lighter weight. You then “drop” or reduce the weight and go to failure.