Taken from Wikipedia :
transfer speed – added a new transfer type called Super Speed or SS – 5 Gb/s (electrically it is more similar to PCIe Gen2 than USB 2.0)
more bandwidth – instead of one-way communication, USB 3.0 uses two unidirectional data paths: one to receive data and the other to transmit.
So each usb 3.0 connection has what you could call 2 lanes. But physically, I think you would see only 1 lane (though I'm not certain of that).
Usually, I think that USB cards may have many ports, but only 1 lane. So let's say you have a USB 3.0 card with data transfer capabilities of 5GB/s and 5 ports. If 2 ports were in use, each would have a bandwidth of 2.5GB/s. If all 5 were used at the same time, each would have a bandwidth of 1GB/s available.
I hope this answered your question,