Yes, after completing high school in the science stream, you can pursue a degree in Commerce, or B.Com. Most universities and colleges, regardless of the stream in which you completed your high school, accept students for B.Com. Nevertheless, it is good to have at least basic knowledge of subjects like accounting, economics, and business studies, which generally fall under the commerce stream. So, some institutions may have certain eligibility criteria, so check with the university you are planning to go to for its eligibility criteria for joining B.Com.
There would be some added efforts to comprehend subjects like accounting, taxation, and business law as one would shift from science to commerce. If you have interest in finance, business, or management, it would adapt you very easily. B.Com opens a large array of careers including banking, finance, marketing, and entrepreneurship. Moreover, one can even take professional courses such as CA, CS, or MBA upon the completion of B.Com for even more enhancement in their careers. It is a fulfilling decision to move from science to commerce with dedication and interest.