This is a mini Scoreboard for Battleground and arena.
It holds only 2 columns. The first column is the player names.
The second column is either "Damage done", "Healing done", "Honorable kills", "Killing blows", or "Honor Gained", choosable at the top of the window thru check buttons.
The window will automaticaly be shown upon entering a Battleground / arena, and it will refresh ervery 3 seconds. These default values can be changed in the options menu (top-right of the window).
If you close the window, there will be no refreshing. When you open the window, the refreshing will continue.
Console command to show the window is /bgscore.
Also if you want to bind a key to toggle showing the window, go to Game Menu, Key Bindings and scroll all the way down until you see BGScore, then assign the key you want to Toggle BGScore Window.