Hello Shivam,
BBA and CA are two different courses. As CA is a self study program you can do a BBA program along with your CA. However, as CA is a very tough program and would need a lot of focus and hard work so, you should plan both CA and BBA only if you feel that you can do justice to both the programs. The criterion to do CA & BBA is +2. For BBA you need to have a good percentage also, few of the Universities may ask you for an entrance exam.