An E2MOM — "every two minutes on the minute" — runs two-minute rounds instead of one. This preset loads ten of them for a 20-minute piece. At the top of every two minutes the timer calls the round; you do your work, then rest on whatever time is left before the next.
The longer round is for work that will not fit into sixty seconds: a heavy barbell complex, a higher-rep set, or a movement that needs a longer effort followed by a real recovery. Press start to run all ten rounds, or open the editor to change the round length and the number of rounds.