What is work replacement ?

Hi I wonder if some one can explain about work replacement on student visa. My brother is in UK on student visa and I own a business can he work unpaid on my business any how?
Kind regards

It is not work replacement, it called work placement. If the tier 4 sponsor mentioned on student's CAS that the student have to work in a real life environment as part of his or her course then the student have the right for work placement. And student can only work in a place which has been mentioned on his CAS.

Under tier 4 rule student would not be able to work even an unpaid job if he is sponsored by a private college.

Thanks for reply. He is studying in private college can his college allow him for work placement ?

The college can only allow work placement if its a part of the course and if they mentioned it on the student's CAS. Also student is only allowed to work on the place which the college has mentioned on the CAS.