They are basically copied from thetop of
http://orgmode.org/worg/org-tutorials/encrypting-files.html
The first line loads epa-file (epa-file.el --- the EasyPG Assistant, transparent file encryption )
The second line looks like a way to call epa-file-enable if it hasn't been enabled. You can just call epa-file-enable, and it does the check too, but this probably avoids a minibuffer message when it is already loaded. I think this function provides a handler for files ending in .gpg which need to be en/decrypted by gpg.