Foto Timer for Android is a free, open source app that can count and beep. It helps with repeating tasks, such as at the gym. People also use it for developing analogue film, or for meditating.
Foto Timer is working with "processes", which define how Foto Timer counts, and how often it beeps. Processes can also be "chained" together, meaning that a process can automatically launch another. There is almost no limit to how complex your timers can be.
If you want to see what Foto Timer looks like, take a look at the manual. If you prefer a "how to" approach, learn how to use Foto Timer for Tabata exercises.
Foto Timer contains absolutely no AI whatsoever.