Hello and welcome to the forum.
The good news is that, unlike most of the display messages that get posted on here, this one is absolutely nothing to be concerned about.
I think you'll find that's AvSpdB; it's showing you the average speed recorded on the second trip computer.
There are two trip computers, Trip A and Trip B. You can cycle through the trip computer readouts by pressing the button on the end of the stalk. A long press resets the appropriate trip computer.
There's a full description of how all this works in your owner's manual.