Hi, to become a lawyer you will have to clear various law entrances after 12th exam. Some of the exam namely are CLAT, BLA, MH CET LLB, IPU CET Law etc.  After clearing the exam you shall get admission in various top law institutes. The course will be 5 year integrated law program. in major you will be studying BA.LLB and other courses like BBA LLB, BSc LLB is also pursued my many students.
After 5 year of law studies, you will have to appear for AIBE entrance exam so that you can practice law in future. Good Luck.