Somya, there are 2 ways to study to become a CA. One is after 12th and one is after Bachelor's. And there are 3 levels to become a CA:

CA Foundation

CA Intermediate

CA Final

You can join CA Foundation right after your 12th. There is no minimum aggregate and subjects that you should take to study CA. So you need to register with ICAI and complete a mandatory study period of 4 months and appear for CA Foundation exams. Once you clear your CA Foundation, you should register for CA Intermediate and complete the mandatory study period and article ship and join CA Finals. Now there are 2 ways to get into CA Intermediate. You can complete your CA Foundation and then join CA Intermediate or you can also have a Bachelor's degree with Commerce as a subject and then secure an aggregate of 50-60% and then study CA Intermediate directly through Direct Entry scheme. For more information, please visit the official website at: https://icaiexam.icai.org/index.php