When looking through the various townhalls, some of the bases have one barb, some have two and some have none. What do these represent?
In Clash of Clans some townhalls have barbarians in place to signify your Unused attacks.
Basically, those are the amount of attacks you have left. Each barbarian is equal to one attack.
You can attack the other clans with your troops, but you can't use any more barbarians (e.g. attacks) than you have.