They appear to be large humanoid creatures that are covered in fur with colors that range from brown to reddish. Although most gnolls are not particularly clever, they do speak a variety of languages with varying degrees of fluency (they also have their own native guttural tongue).
The leaders of gnolls are related creatures called flinds. Flinds are somewhat smarter than their cousins, a bit broader but also shorter. Both Gnolls and Flinds wear what appears to be “found” armor and clothes, taken off their victims. They are known to enslave and/or consume other humanoids they find.
Gnolls are quick to engage in combat, but if they fear they will lose the battle then they will flee. If fleeing is not an option, then it is possible they will surrender.