Teleportation is the ability to transport from one place to another in a matter of seconds. According to John, there is a certain range. So technically you cannot teleport from the New York to Korea in one jump.
There are beings powerful enough such as Cassandra Smythe that can remotely teleport things as big as cars to teleporting bullets out of multiple guns. Stephen Jameson also demonstrated this ability in Son of Man when he teleported Hugh Bathory to his hand before throwing him in a space-time vortex. Another ability displayed was when John was able to teleport at such speeds he ended up in five places at once. This seems to be the extreme of the ability due to the fact he was extremely fatigued and disoriented.