POE Stands for Power Over Ethernet. There are some routers that have the ability to send power out over the ethernet cables and power the units on the other end (sort of like USB). The Airsight Cameras can take adantage of this with this cable.
In fact, these cables come in a pack with two different cables in it which allow it to also send power over ethernet (POE) without having one of these special routers. Here is how it does it: