Break this down into steps

1. sudo is a command used in several varieties of Linux and other *ix operating systems to allow a command to be executed with root privileges.
2. pgp is an encryption|decryption system. The -e option "-e <plaintext_filename> <recipients_userid> Instructs PGP to encrypt a plaintext file with the recipient's public key." (see PGP documentation at www.freebsd.org).
3. chown changes the ownership of a file. In this case, it changes the ownership of test_san.dat.pgp to the user with the id of "sann"
4. Similarly, chgrp changes the group membership for the file (*ix-like operating systems divide users into groups. File access rules can be restricted to different for members of a specific group than for those not in the group).
5. &> is file redirection.
6. The parentheses are used for grouping.
7. and most importantly read the documentation.

I've found that the man pages are wonderful sources of information. If the man pages aren't on your system, The FreeBSD Project, SUSE, and many others maintain on-line documentation sites.

Editorial corrections