The media rate is the speed at which the network card operates. On most cards, it's either 10 Mb/s or 100 Mb/s. This display also shows what form of duplex the card uses. Most cards run at half or full-duplex transmission:
The easiest way to illustrate this is to think of a road. If the road has two lanes, it's full-duplex, because cars can drive in both directions at the same time without obstructing the other lane. If the road has only a single lane, it's half-duplex, because there can be only one car on the road at a time.
When you examine the media rate, check the speed, the form of duplex, and what the hub supports. Not all hubs support full-duplex.