Hallo everyone, long time no see ^^

I'm working on little project of mine, but I need some lore assitence. To be more specific:

http://s26.postimg.org/ynbj2e5h5/Akaviri.png

Does anyone know the meaning of the symbols? I don't recon mentioning it ingame (however I wouldn't be suprised if Esbern said something about them and I did't pay attention/was interrupted). Any help will do