The visit won't be very complicated, but to apply for your SIN (Social Insurance number) you'll need to bring your: confirmation of permanent or other proof of status in Canada like a work or study permit, and your passport.
I'm not sure what got you confused here. I think the body itself is self-explanatory. Proof of Status is a person's legal standing/status with which he/she resides in a country. For students, it's study permit/visa. For working professionals, it's work permit/visa. Similarly there can be temporary resident visa for tourists and visitors, and so on.
Here's the definition of Proof of Status from the US Embassy in Laos
Proof of Status - This term refers to the legal status of the petitioner in the United States. A petitioner must be a U.S. citizen, or a lawful permanent resident currently living in the U.S., if he or she wants to bring another immigrant to the U.S. Therefore, a petitioner must present a U.S. passport or a valid green card--residency must not have expired (which may occur if a petitioner has been out of the U.S. for over 6 months). Appropriate evidence is necessary.