can a 12th student drop a year for ILETS...??

You needn't take a drop for IELTS. IELTS is just a Language proficiency test which is an exam taken by Non Native English Speakers to study or work in Native English Speaking Countries like UK, US, New Zealand, Australia, etc. Your IELTS score determines your English proficiency. There are many Coaching Centres that help you in IELTS Coaching. It is an hour a day or 3 hours a day maximum. The coaching might be for 3-6 months based on your pace and you can attempt the exam whenever you are ready. Infact, IELTS is an easy exam which can be aced if you practise enough at home. You can check the exam formay here: https://www.ielts.org/about-the-test/test-format. But taking a drop for a year just for IELTS is not advisable. You can do it while pursuing your education.