BoxCryptor protects and encrypts the contents individual files and stores them in the BoxCryptor Folder. As each file is encrypted individually, BoxCryptor does not hide the file and folder structure. To get additional privacy, the Unlimited version can also encrypt the names of files and folders.
The BoxCryptor Folder (e.g. Dropbox\BoxCryptor.bc) is just a regular folder which you can browse like any other folder. Finder on Mac OS X simply shows it as a single "file" (or rather package) due to its .bc extension. By right-clicking it and choosing "Show Package Contents" you can browse it also on Mac OS X.
The important part is, that you cannot open the encrypted files without BoxCryptor and the correct password - even if you're able to list the files (which also does not give you much information if filename encryption is enabled).
Hope I could help you,