Is Cloud SQL v1beta4API is to access Cloud SQL Database Instance or Database Data if this is only to access Database Information then how to access/Query data in the database from an Android client application or any other application?
The Cloud SQL Admin API is for administrative tasks in managing an instance. It can start, stop, create, or perform other administrative task to an instance.
If you want to build a REST api to access the data, I would suggest using something like Cloud Functions or Cloud Run.