I have an English question on this post -> Firebase: Should I add GoogleService-Info.plist to .gitignore?

While it's not the end of the world if you commit GoogleService-Info.plist (similarly, on Android, google-services.json), you're better off leaving it out for one big reason: You're making it clear that others who build your code that they should be setting up their own Firebase project to host its configuration and data (because your project simply won't build with that file missing).

"It" is "GoogleService-Info.plist". "Leave it out" means to not include that file in the group of files that are uploaded into the public repository.