The Teleporter, as the name suggests, allows you to teleport instantly between two locations.
It then has to be linked to a second teleporter, which can be done by shift + right-clicking the teleporters and setting both to the same frequency.
When powered, you can right click the teleporter to move to the second teleporter.
You can only have 2 teleporters with the same frequency. However, you cannot use a Portable Teleporter in order to reach either Teleporter that is on one frequency.