This library is used to gain direct access to the functions exposed by Daniel J. Bernstein's nacl library via libsodium or tweetnacl. It has been constructed to maintain extensive documentation on how to use nacl as well as being completely portable. The file in libnacl/__init__.py can be pulled out and placed directly in any project to give a single file binding to all of nacl.
The libnacl code also ships with many high level classes which make nacl cryptography easy and safe, for documentation please see: http://libnacl.readthedocs.org/