How meteor - android/ios app works?


Everywhere on the internet I see that you run some command and you have a android/ios app.
But I couldn’t found any article, about how that app work?
It communicate with the meteor server? If I put the meteor app online and someone create an account on website could login with that account in the app ? If when I run the command to create the apk, the database has 10 000 items in 2 collections, all that database will be in the apk ? What if the android user open the app and he isn’t connected to the internet?

If you found an article that explain how meteor - android/ios works, please share it.