The usb stick is the gateway between the 6LoWPAN network and your usual WLAN/Ethernet network. From the IP network side, the 6LoWPAN devices appear as IPv6 devices. The conversion between IPv6 and 6LoWPAN happens in the USB stick. Then, the packets are sent into the radio network on 868 MHz.
The USB stick provides two USB endpoints:
LEDs off: no power supply or rather not connected to a USB port
LED glowing green: normal operation
LED flashing red (slow): in provisioning state
LED flashing red (fast): in bootloader
LED flashing green (3x slow): provisioning successfully completed