hello ,thanks for reaching out us for help u will surely be beneficial  of this answer.

ICRB stands for ISRO CENTRALISED RECRUITMENT BOARD(ICRB). The exams are conducted by ICRB for ANNUAL RECRUITMENT OF SCIENTIST/ENGINEER 'SC' WITH BE/B.TECH OR EQUIVALENT DEGREE IN ELECTRONICS, MECHANICAL AND COMPUTER SCIENCE

You can refer to the following link for more information.

ISRO

please refer above link for more details.

keep up hope

all the best

best regards for your future and  seccessful career.