If two persons have "or" on the names registration of a vehicle, it means that either person can act as the sole owner of the vehicle. They do not need to agree on any decisions regarding the vehicle, and either person can sell it, transfer ownership, or make major repairs without the consent of the other person.
It is important to note that the ownership of a vehicle is determined by the registration, not by the title. The title only shows who has legal possession of the vehicle, but it does not necessarily indicate ownership.