Dear candidate, in your admit card of class 12th , there may be a column named Unique ID, Student number or registration number of multiple digits. That is your roll number which should be written in your NEET UG application form. For more details, you can check:

https://medicine.careers360.com/articles/how-fill-neet-application-form#:~:text=Step%203%3A%20On%20the%20hard,email%20ID%20and%20mobile%20number.

Hope, it helps!

You have to enter the number present in your admit card of your 10+2 in that place. The roll number is the unique number provided to the students which are mainly the seat numbers of the examination hall.

For NEET latest news you may visit the link below:

https://medicine.careers360.com/articles/neet

I hope this helps.