This window allows you to edit the settings for this newsgroup folder. See the New Newsgroup window for details, since the interface is the same.
There is an additional 'Last Download Date' label, which just gives the date and time when you last downloaded news for this newsgroup, and the 'Folder Location' label, which is where the messages for this group are stored (the folder given is in the folder pointed to by the NewsCoasterData: assign).