Hey Paritosh,
BCA or Bachelor of computer Application is a three year full time graduation course. People who want to build their career in the field of computers and Information Technology can opt for this course.
Best Colleges in Patna are
1. Tapindu Institute of Higher Studies(THS), Bihar.
2. Ram Krishna Dwarika College(RKD)
3. Amity University
4.Anugrah Narayan College(ANC)
5. Patna College
6. Bihar National College
7. Magadh Mahila College
8. Birla Technology of Technology
9. Aryabhatta knowledge University(AKU)
10.Jagat Narain Lal College(JNL).

Hope it helps:)