Hi Dinesh

With 1st, 2nd and 3rd attempts, it means that you will have three chances to appear in the entrance exam. Since, its an online exam, you will get to see your scores as soon as you attempt the paper. In case, you are not satisfied with your scores in the 1st attempt, you can opt for 2nd and appear in that too, similarly, if not satisfied with the 2nd attempt scores, you can appear in the 3rd attempt. The 1st and 2nd attempt is scheduled to be conducted from April 19 till May 9, whereas, third attempt will be held on May 11, 2018.

Know more from the link below :

 MU OET 2018

All the best !