Yeah, it's pretty confusing without any context, so i'm going to try and hopefully explain it a bit.
A world was created and two gods were created, the Bionis and the Mechonis(the Mechonis is the one in the wallpaper). They fought and are pretty much in deadlock, so the Mechonis was somehow made inhabitable, and many populations are able to live and thrive on there.
The two guys are named Shulk(the one with a red blade, left side) and Reyn(generic-ass sword, on right) and are 2 out of 7 party members. Shit is pretty confusing for me, so I don't blame you, it gets even more confusing once you actually play the game.
Also, 7/10 for your wallpaper.