MakerICE Adapter AVR - How it works
How to use the connector?
Connect one side of the 10-pin IDC flat cable to the programmer in the port marked AVR as shown in the picture below:

Flat cable connected to Atmel-ICE
After that, connect the other side to the adapter breakout as shown in the picture below:

Flat cable connected to MakerICE Adapter AVR
Connect the adapter to the supported board of your choosing:

MakerICE Adapter AVR connected to AVR supported board