A single-entry visa allows you to enter Canada once.
When you arrive at the point of entry in Canada, an officer of the Canada Border Services Agency will make sure you meet the requirements to enter Canada.
The officer will authorize your stay by placing a stamp in your passport and/or issuing an additional document.
If there is no stamp, a handwritten date or document in your passport, your temporary resident status will expire six months from the day you arrived in Canada.
If you were given a visitor record, student or work permit, the expiry date is marked on the document.
If you leave Canada during your authorized stay, you must get a new visitor visa to re-enter Canada.
There are two exceptions: you can visit the United States or Saint-Pierre et Miquelon and return to Canada without getting a new visa, as long as you:
return within the initial period authorized by the immigration officer or
have a valid visitor record, work permit, study permit, or a temporary resident permit (authorizing re-entry) and return within the initial period authorized by the officer.