Hi Baskar, showing the Balena logo is normal. balenaOS does not have a desktop it is designed for running containers. Did you create an application on balenaCloud and download balenaOS image from their or did you download balenaOS directly?
For developing container based applications we recommend using balenaCloud, it is designed to make developing and maintain applications on small devices like raspberryPi easier. For more info on how to get start with RaspberryPi and Python on balenaCloud please refer to this getting started guide: https://www.balena.io/docs/learn/getting-started/raspberrypi3/python/. balenaCloud is free for up to 10 devices.
Using balenaOS without balenaCloud is possible but requires more advanced Linux and Docker skills. You would have to do all the things that balenaCloud make easy manually.