POE is the abbreviation for Power over Ethernet and describes the power supply of the connected device via the existing network cable. By using POE you save the external power supply and accordingly the cable laying. The device is then connected to a switch with just one cable to both transmit data and power the device. An easy way to install surveillance cameras!
Please make sure,
a. that the connected device POE is suitable
b. that a so-called POE switch is used.
POE switches are a standard product today and hardly differ in price. Please make sure that the switch is actually a POE switch.