I want to know about option of MS in Australia after BBA in real estate?

First of all, Australia is a very good place right now. Because the real estate sector has been constantly growing for the past decade in Australia. Plus the university has now introduced many standard MS options that you can do after a BBA in real estate.

It would be intelligent to go for the same field you have pursued till now. There are dedicated real estate masters' courses that universities in Australia have. My recommendation would be -

MSc Real Estate Management, or
MSc Real Estate Development

Both of these MSc degrees are not much different. You will learn about investors, developers, occupiers and projects. The primary job areas would be managing and handling real estate operations to make them better somehow. These courses in Australia are accredited in the country so that you can work there without any interference. Because fields like medicine, psychology, real estate etc., need certain certifications to work abroad.

One more option is; MSc in Real Estate Asset Management. Basically, you will be working more with Asset management to keep the functions of an organization smooth. Apparently, it is one of the real estate areas that is getting more popular nowadays. And if not impressed by any of these, you always have engineering sectors like construction. Engineering is a nice area to work in real estate, just the approach will be diverted.

You can also look for the universities that suit your interests and objectives for the same. If you get stuck at any point while trying to figure out the suitable universities for your profile, you can check out this FREE school explore tool and get the task of shortlisting the right school done very easily.