So you are newbie for app inventor 2 community and 🤔 about how to make a countdown don’t worry 😉

Video

Preview

Clock component trigger “

” when internal timer expired

When you set timer enabled and timer interval to 1000ms. “when.timer” block triggered after 1second thats clock component working mechanism.

So if you want make a countdown like countdown from 30s and display it on a label you can use this block all this blocks is simple

And here settings for timer block.

And here you can find aia file

ai2.appinventor.mit.edu/?galleryId=5174691295789056

I hope you understand