When we add a user to the workspace, we grant them access to editing apps in the workspace. When a user with edit rights opens an app, it is locked to all other users. In the following screenshot, which shows the User1 workspace, we can see a label on top of the app icon, with the name of the user editing the app:

Only one user can edit the app at a time in the workspace. The app is unlocked when the user editing the app closes the web browser tab that's used to edit it.