Hii Ashok!
Generally CLAT entrance examination is the way to get into UG LLB Colleges. The minimum marks required in class 12th as per the eligibility criteria for the exam is 45% for general category and 40% for reserved categories. But still, you should work hard and get good marks in class 12th.  You can visit the following link for more details -
https://www.google.com/amp/s/law.careers360.com/articles/clat-eligibility-criteria/amp
Hope this helps.
Good luck!