Most values here are pretty clear i guess ;)
The data presented here can only be accurate if you hunt in a team. If not the mob count will be wrong as i can't trigger a new loot. As a consequence of that most other info will be crap aswell!
The orientation of the loot info can be changed from vertical to horizontal in settings. The loot info window is set to stay the top window so if you run EU in window mode you can move it over the window to see the stats as overlay.
The background can be set transparent via context menu for the overlay use.
As the loot tracking can't get the tt value of non stackable items the value here can be inaccurate. If you want to fix that go to the new run window -> loot items and correct the value of the item then use the context menu action "Update loot info" in the new run loot items.