I presume that's the popup screen you get when you click on a raging battle.
I'm doing this by heart so sorry if I forget something.
2 columns containing the divisions involved in the fight on both sides. the ones in the top sections are actively involved in combat, the ones in the bottom section are in reserve. Units in reserve have a certain chance every hour to join the fight, if there is place on the frontline (aka if a frontline division pulls out). you can see the percentage chance by mousing over them, I believe it depends (amongst other things) on the commander's skill level.
On the far top you see different effect that, unsurprisingly, have an effect on the combat

Things like nightfall, mud, frost affect both sides. also on the top side, you see the tactic either side is using at the time. These tactics are chosen by the commander leading the fight, a higher skill level commander has a higher chance of picking a tactic that counters the opponent's. If one side effectively counters the other's attack, this is visualised by a crumbled arrow on the side of the failed side. If your tactic is effectively countered, your combat efficiency is lower and you deal less damage while taking more I think.
Anyone notice anything obvious I missed?