Hello,

It looks like a registration number for the applcation you have applied. So look for a blank where there will space to write this registration number. As the form varies from places to places. Better go to your admission department or the department that deals with the marksheets and registratiion for different exams. They will help you accurately how to do it. Many students do every year so they know proper way to do. Any improper filling will lead to rejection so ask to the faculties in your college.

Hope it helps!