Hi Divyam

OTBS is Online Test Booking Schedule which means you have to book a date, time and centre for appearing in the entrance exam. It is same as slot booking. Since it is an online exam, it is important that you book your slot timely to avoid hassle. The OTBS for 1st and 2nd attempt is going on from March 31 till April 7. I will suggest you to book your slot as early as possible. Refer to the link given below to book your slot for MU OET 2018.

https://engineering.careers360.com/articles/mu-oet-slot-booking

All the best !