Breaker is a timer that will alert you when it's time to take a break or keep track of how long you've been working, depending on how you configure it. Program your "work time" and it'll tell you when to stop working.
If you're keeping track of your productivity, you can tell it to keep track of how long you've been working and alert you when it's time to stop and take a breather and then again when its time to go back to work. Breaker can be set with how long you want to work before the app alerts you, how long your break should last, and how frequently the app should loop those two cycles.
This way, the app is flexible enough to use with the Pomodoro style, where you should work intensely for 25 minutes, and then take a 5 minute break, but also flexible enough for the 20-20-20 rule, which says for every 20 minutes you stare at a computer screen, you should take a 20 second break and look at an object 20 feet away to reduce strain on your eyes.