Except for English both rounds were pretty easy in the Aptitude prespective.
A choice of 1 - 40 number is given and accordingly a topic is given. If u dont like the topic u can go for another number but this will be final. I took number 1 and got the topic "Technology in Sports". Now I had 2 mins which I could use at my discretion in which I had to speak a minimum of 1 min which should have a proper Introduction , pros , cons and a conclusion. I took 15 seconds to jot down my points and spoke for about 1 min 15 seconds.
P.S. :Do utilize your full time , 30 secs to prep and 1 min 30 secs to speak.
The Interviewer checked my resume first and asked questions regarding my internships , which new technologies was I working on. Although I had been learning R at that time the interviewer was focused more on knowing about my approach in web development on a full stack even though I hadn't mentioned anything related to that in my resume. Since I had a previous experience in that field it was really easy for me to explain. I was not asked to write any code or syntax but make sure you have brushed it up because many of my counterparts were asked so.
Vocabulary has to be worked on for English. General aptitude AIMCAT related free tests will help.
For JAM read about various technologies in the current market like Blockchain , IOT , Industry 4.0 and so on..
For the final round be thorough with your resume and your soft skills as well.
Lastly , Stay Confident and keep a calm mind!