"!" is the same as "not", so "!isRound" is equivalent to "not isRound". "state = 2" adds the condition that the tournament is currently running, which would prevent the event from firing in a tournament countdown, so that's a good addition that I forgot.
There's no way in the event formula (conditions) to know that the next level is a break, so you can't code up a generic event that will always fire only at 60 seconds before a level change before a break. But you can "hard-code" an event to do this, which would depend on a specific schedule.
As an example, let's say you have a blinds schedule where you have a break after every 3 rounds. So, there's a break after round 3, round 6, round 9, and round 12. Your event conditions could be:
(not isRound) and (state = 2) and (secondsLeft = 60) and ((roundNum = 3) or (roundNum = 6) or (roundNum = 9) or (roundNum = 12))
The only issue with this is it is directly dependent on your blinds schedule. If you change the order of your levels, the event will still fire on the same rounds (3, 6, 9, and 12), regardless of whether or not there is a break directly after those rounds.