If your application is not approved, the visa office will send you a letter explaining why your application has been refused. An application might be refused for several reasons:
You have not shown proof that you have enough money to support yourself while studying in Canada.
You have not passed the medical examination if one was required.
You have not satisfied the visa officer that your primary intention in Canada is to study.
You have not satisfied the visa officer that you will leave Canada at the end of your period of study.