The visa authorities wish to confirm your background when you want to go to Canada. Hence, a biometric check. First-time applicants need to apply for biometrics. Repeat applicants or applicants who have already given their biometrics as a part of their visitor or work visa probably don't have to do it since the information is likely to be valid still. You must pay the biometric fee, get the biometric instruction letter that outlines the process for you, and then visit an official biometric collection center to provide the necessary information. Remember, any documents or proof you provide should be genuine. Submitting fraudulent information is one of the important Canada student visa rejection reasons. Find out more about it here.