Hello dear,
Mathematics is a universal subject. If you choose to pursue aB.Sc. in Mathematics, there will be a lot many options that you will be able to chose from. You can work in different areas such as:

Mathematician - You can choose to pursue research (become a scientist) in your area of interest in Maths. And if you choose research, you can go into the teaching sector also. Check out institutes like TIFR Mumbai, IMSc Chennai, Harish Chandra Research Institute Allahabad.

Chartered Accountancy - If you like auditing, taxes and accounting, you can think of preparing for CA too.

Banking - Banking is another sector that you can get into with Mathematics.

Actuarial Sciences - If you love data and maths, actuarial sciences would be a great field for it.

Data Analysis/Operations Analysis/Project Development - If you want to work in the private sector, you can look at these profiles.

Military Operations - Mathematics degree would also allow you to work in the military sector, scientists are always required to work with military and development (DRDO, ISRO, NAL, SETS, etc.). You can also join the navy as a Commissioned Officer in their education or logistics branch.