Hello!
I am working on a school project with some esp8266 and i have coded them to send their data to firebase. It is a parking spot project, so i want to make an app that i can see which spots are occupied, but it's my first time with the combination of firebase and appinventor and i am not so sure what to do.
I just need to figure out how to get these 0 or 1 numbers to the appinventor code
Are you using secure rules for your authenticated user/s ?
If rules are read/write true then see here for an example:
Also read here too
http://ai2.appinventor.mit.edu/reference/components/experimental.html#FirebaseDB
https://rominirani.com/tutorial-mit-app-inventor-firebase-4be95051c325
http://kio4.com/appinventor/8BfirebaseDB.htm
Since you are new you must read the tutorial or guide of the mit app inventor component first 
