KeePassX 0.4.3 > Menu > Groups > Add New Group > (Group Preferences) > '>' lists 68 group symbols. What do these 68 group symbols stand for in detail? The KeePassX handbook does not explain that. I could not find the answer in the documentation of the keepassx project either.
They are icons you can choose from to associate to the group you are creating. No hidden meaning intended, I think.
The icon will be shown near the name of the group in the groups' list on the left of the main window.