sent and received bytes

General question. What do the bytes sent and received mean in the right bottom corner of my screen (when hovering over the little screens). Can you say anything about BB speed from those readings. Sometimes they're v low such as 28,000 bytes what does that mean? Normally they are 4 million sent and 31 million bytes received or something.

The more bytes the more data you've transferred, if you are good at the maths you can work out your BB speed, or use tools like tbbmeter (yes a self plug http://www.thinkbroadband.com/tbbmeter.html) to do this maths for you, and produce an easy to follow graph.