Hello,

PhD means doctor in philosophy in a particular subject. It's a higher level of study.. if you complete your research work then you will become a doctorate person.

You are completed your MSc in mathematics which is great. And may be want to phd in mathematics also. In this subject phd complete time duration 3 to 10 years in abroad. It's depending upon specific field of study, preferable training and good mentor as well.

All the best.