bundle
Like a packed lunch in one bag, a bundle is your app’s files zipped together so a phone or store can install or load them.
With React Native and Expo there are two common kinds. A JavaScript bundle is the code your app runs, packed so it loads fast. A store bundle is the full installable app that Apple and Google accept.
Bundles matter because they are what you ship and what users run. The store bundle goes to the App Store and Play, and the JavaScript bundle is what the app downloads when you run or update it.
In practice: Expo creates a development bundle when you run the app. For release, you build an .ipa for iOS and an .aab or .apk for Android using Xcode or Android Studio, then upload to the stores.