http://www.extremetech.com/computing/197145-reversible-usb-type-c-finally-on-its-way-alongside-usb-3-1s-10gbit-performance
That should explain everything =]
Also,
"If you find you're running low, charging is quick with the USB Type-C plug. It's reversible, so there's no more guessing which way is up," says the Nexus 6P webpage.
USB Type-C plugs have high endurance and longevity. They are designed in a way that endures no less than 10,000 insertion and extraction cycles.
USB Type-C connectors can transmit DisplayPort signals at up to 4K resolution. The new plug can also handle electrical power of up to 100W.
USB Type-C connectors can also be used for data transfer as well as charging devices. Apple's new MacBook has a single USB Type-C port that allows for charging or transferring data. Google's latest Chromebook Pixel also features two USB Type-C ports, which can also be used to charge the device or transfer data.