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