Basically 2>/dev/null will hide the error messages, more technically, Usually 1 for standard output and 2 for standard error. Default setting in both of them are associated with monitor (console), by using redirection operator (>) moving the messages to specific file, in this case it is null so it will not print on your screen.
Whatever error generated by mount will not be seen on the screen. -- This message posted from opensolaris.org
