It typically means when a person is overly jealous and obsessed with people and things they deem as "theirs". For example a gf making a bf delete every single girl on his FaceBook for absolutely no reason, or yelling at a friend for simply touching your newest purchase.
I agree with the person above me. It's a form of control. It's also not a great quality to possess and would highly recommend taking steps on correcting this,... Chances are you will not ever live a for filling life if your always claiming what's yours and never sharing it with others.