It has the intelligence to first quickly charge one device at 15 watts (5 volts @ 3 amps) and another device at 7.5 watts (5 volts @ 1.5 amps). Once the device has finished charging from 15 watts, the Universal 22.5 W Dual Port USB Type-C Charger will then provide 15 watts (5 volts @ 3 amps) to the other device so that it can charger faster.
The Google charger comes with a USB Type-C to USB Type-C cable and documentation.
The 1.8 m long USB Type-C to USB Type-C cable should be able to support USB 2.0 (480 Mb/s) speeds. To charge your USB Type-C based device, just attach the cable to the USB Type-C port on both the Universal 22.5 W Dual Port USB Type-C Charger and your device.