Data rate is measured in bits (b) per second, and remember there are 8 bits (b) in a Byte (B).
USB2 operates at 480Mbps (480,000,000 bits per second) which is approximately 60MB/s (megabytes). In reality you get a lot less than that without the amount of overheads involved.
It can cause all sorts of confusion when different sources use decimal or binary multiples when working things out. I've used the decimal multiples to arrive at 60MB/s - if you used binary multiples you would get a different answer (but still a ballpark figure that is fairly close to 60MB/s)