hi,

three years llb course is applicable for those who has completed bachelors degree, in case you want to apply for llb course after completing 12th, you have to apply for five years integrated course of llb i.e b.a llb or b.com (//b.com) llb or bba llb.

As per JAG ENTRY SCHEME 26TH COURSE (APR 2021): Candidates must complete 55% aggregate marks in LLB Degree (three years professional after graduation or five years after 10+2 examination). The applicants should be eligible for registration as an advocate with Bar Council of India/State. applicant  should be from a College/University recognized by Bar Council of India.

follow the below link to know in details:

https://joinindianarmy.nic.in/writereaddata/Portal/NotificationPDF/JAG_MEN__26.pdf