Hello Ravneet,
Yes, you can study LLB after completing BA. It is an 3 years course. Any degree holders can do LLB, irrespective of their age.( from the academic year 2017 , the bar of age limit is revoked) whoever interested can pursue their law degree. LLB Admission is done either on the basis of marks obtained by candidates in qualifying degree or through a relevant entrance test. Students who are in final year of their graduation can also apply for entrance tests conducted for LLB admissions .There are various enterance teats conducted for LLB admission in India