The front says "Serbia" with the crest of Serbia on it (double headed eagle with 4 c's which stand for "Only Unity Saves Serbs").
The back says "God saves Serbs" but litteraly it says "God watches Serbs" in the sense of a father watching his children. You could say it has the sense of "takes care of"
Underneath that are three fingers being put up, which stands for Orthodoxy, cuz those are the 3 fingers we use to cross ourselves with.
I'm not sure where you found this or what it means to you, but its a SUPER nationalistic shirt. Not that that's a bad thing, i'm just letting you know. If you want more information about these symbols just ask (cuz there's a lot of history behind everything on that shirt).