Hii Khushboo!
There are various entrance examinations conducted which provide admissions in bba course such as SET BBA,  IPMAT etc., The general procedure is, you need to visit the official websites of the respective examination you are interested in and fill the application form. Once the process is complete, you get an admit card. You sit for the examination. Then the result is released along with the cutoffs. You need to apy for counseling and may get a seat.  The Eligibility criteria differs for each exam. You can get full details on the same in the link given below-
https://www.google.com/amp/s/bschool.careers360.com/articles/top-5-bba-entrance-exams-know-exam-pattern-eligibility-criteria-and-selection-process/amp
Hope this helps.
Good luck!