If you look at it without un-encrytion, there will be nothing. If you don't have the right password, it should refuse to un-encrypt.
But a SparseBundle disk Image is a Virtual Disk implemented within a file. The size of the file indicates the maximum size the Virtual Disk can grow to at the moment, but does NOT indicate exactly how large the files inside might be.
It is entirely possible to create an encrypted SparseBundle disk image and get a 531GB file that has nothing inside. This is especially true if you did not have read access to the files in the original Folder, such as certain system files accessed from a regular User ID.