It is an abbreviation for Power Over Ethernet.
It is a function to receive electrical power via LAN cable (max. 100 m) by using a PoE+ hub or injector. No AC Adapter is needed, so the number of wires can be reduced when wiring up the devices. Also, it is possible to install them in where electrical work is difficult to do.
The power-supply capability (* output power value at the PoE hub end)
PoE = 12.5W
PoE+ = 25.5W
* PoE+ is downwards compatible, so a PoE+ hub works with PoE devices. But a PoE hub does not work with PoE+ devices.
* Cable: category 5e or above, max. 100 m