Explanation about CSBC:

The CSBC is a Central Board that is made to fulfill the recruitment of required places on Constable posts of different Regions that's office is situated Sardar Patel Bhawan, 6th Floor, Block-A/626, Jawahar Lal Nehru marg Patna, Bihar.
Visit it's Official website here.

General idea About CSBC Department.

This department works to complete the appointment for Home Guards, Fire Services, Forest Department, Prohibition Department etc. It helps to conduct the exam (sometimes it might be based on other methods) but mostly now the exams for constable of different department (in Bihar) are conducted by inviting exam applications online method. They release notification and publish that to public and interested and eligible candidates can apply for such posts.

CSBC - Full Form

 "CBSC Full form is - Central Selection Board of Constable."