USB is a serial input/output technology for connecting peripheral devices to a computer. SuperSpeed USB 3.0 is the latest implementation of this standard, and it provides higher bandwidth and new power management features.
Transfer rates can attain up to 5 Gbits/s as opposed to USB 2.0's 480 Mbits/s. This means USB 3.0 is theoretically up to ten times faster than its predecessor.
Your LaCie drive is shipped with a SuperSpeed USB 3.0 cable to ensure maximum data transfer performance when connected to a compatible USB 3.0 port. The cable will also work when connected to a USB 2.0 or 1.1 port, but drive performance will be limited to their respective transfer rates.