Why isn't "visiterar" accepted here? Is it more finlandsvenska?
So what would be the difference between sin and hans?
Sin refers back to the subject, hans doesn't.
If you're like me, and consistently get subject and object mixed up, it might help to remember sin as "his own".
Han besöker sin bror= He visits (his own) brother
Han besöker hans bror= He visits (some other man's) brother.