The Biometric Residential Permit (BRP) is your student visa, and comes in the form of a card that is the size of a credit card.
To obtain the card, you will have to go to a designated post office within 10 days of you entering the UK. You need to bring along the Biometric Notification letter which was issued to you when your visa application was completed. The notification letter will indicate the exact post office where you can collect your card. In some cases, the designated location may be your school.