1. This is the front of a network switch.  Sometimes the ports are also on the back, but this is typical.  You can also see here the power light and the indicator light on the ports letting us know there is activity.  The cables plugged into the switch are ethernet.  Your POS or credit card terminal may utilize a switch.  

2. Here is a closer image of the front of the switch.
3. Lastly, this is the top of the switch - as you can see the A/C adapter plugs into the back.  The position or type of power cord may change from switch to switch.