A TRV is an official counterfoil document issued by a visa office that is placed in your passport to show that you have met the requirements for admission to Canada as a temporary resident.  It is often called a Visitor’s Visa.  The Immigration officer must be convinced that you will leave the country at the end of your stay.  The maximum time you can stay in Canada is 6 months.

If you want to extend your visa, you must apply 30 days before your status in Canada expires.  Your original temporary status as a visitor continues under the same conditions until your application is finalized and you have been notified of the decision, The validity of your temporary resident status cannot exceed the validity of your passport.  Therefore, you should ensure your passport will be valid for at least the same amount of time as your requested extension.