There are two types of Temporary Resident Visa: a single-entry visa and a multiple-entry visa. Temporary Resident Visas are valid for a fixed period, whether they are a single-entry visa or a multiple-entry visa. You cannot use a visa after its expiry date.
Multiple-entry visa
A multiple-entry visa allows you to enter Canada several times during the period while your visa is valid. A multiple-entry visa is valid for a maximum of 10 years or one month prior to the expiry date on the passport/re-entry visa, whichever is earlier.
If a multiple-entry visa is approved, it will allow you to enter and leave Canada repeatedly during the validity period of the visa. You must arrive in Canada on or before the expiry date on your visa. You cannot get a multiple-entry visa for a period that ends after the expiry date of your passport. If your passport will expire soon, you should renew it before you apply for your visa.
If you want to visit several other countries or return to your own country before coming back to Canada, you will need a multiple-entry visa. If you plan to visit Canada frequently, a multiple-entry visa is recommended.