Adding ".noindex" to a file/folder's name causes it to not be indexed by Spotlight, so you won't be able to find it (or its contents) using Spotlight. I don't know what that particular folder is for, as I don't have such a folder. I suspect some software created it, but don't know what or what it might be for. If you plan to delete it, I'd advise moving it to the Trash first, but don't empty. Leave it there for as long as it takes for you to be sure all your apps are behaving correctly, then empty the trash if you're problem-free.