Canadian domain names (.ca) require a Canadian presence just like .us domain names require a NEXUS USA identification.
The Canadian Internet Registration Authority, or CIRA, requires that .ca domain name titleholders of .ca domain names or "registrants" have Canadian Presence.
When you reigster a domain name, you need to choose a legal type that matches one in the Canadian presence document at CIRA.
This is usually "Canadian citizen" or a "Canadian Corporation", but there are many other designations for Canadian presence including partnership, association, indian band, and more.
If you do not comply with Canadian presence requirements, then you may have your domain name revoked by CIRA, so make sure you choose the correct designation, and ensure that you satisfy the Canadian presence requirements.