A measurement of data transmission speed. Measures the numbers of bits (a bit is either a "1" or a "0") transmitted in a second.
Loosely following the metric system, bps can also be express in kbps (1,000 bits per second) or Mbps (1,000,000 bits per second).
In wireless systems, this is often either a "peak" or "average" number. Peak is a theoretical maximum - rarely acheived outside of a lab. Average is generally a more realistic number.