CSAB stands for Central Seat Allocation Board. CSAB conducts special round in order to give admission in NIT+ system when seats remain vacant in Institute after JoSAA counselling is finished. It is usually conducted in two rounds and the seat allocation is done based on CRL rank and not category rank. You have appeared in JEE Main. Therefore, to predict your college and branch options based on your rank, you can use the JEE Main college predictor tool by clicking on the following link: https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Hope it helps you.