Hey,
There are lots of career options that you can go for after your 12th depending upon your interest.
Since,you are from Mathematics Background then you can probably go for Engineering Related Fields and can appear for JEE Mains or state specefic Engineering Entrance Exams.
You can go for Bachelor of Science(B.Sc) in different courses like B.Sc in Physics,B.Sc in Chemistry,B.Sc im Mathematics or B.Sc in Information Technology and so on,the list being endless. After this you can do your Masters and then P.hd and become a professor.
You can even change your stream and go for Humanities. You may go for Bachelor of Business Administration(BBA) or Bachelor of Business Application(BCA). You can go for CLAT,if being a lawyer has ever been on your cards.
Hope this helps.
Good luck.