Hey.

if you have completed any undergraduate course like in your case it is BA, you cannot apply for any PG law course or masters in  Law course directly. For admission in any PG law courses or masters course ie LLM the basic requirement is a bachelors in law degree ie either 5 year integrated law course or a 3 year LLb course.

So if after completion of BA course you wish to pursue law you will have to go for LLb degree. the duration will be of 3 years. Then after LLB if you want to specialise in any area of law you can go for masters course or PG course.

Best of luck