why + symbol is while viewing file permissions ??

ACL (Access control List) which are used to define more fine-grained discretionary access rights for files and directories.

Setting an additional user read access
=======================================
setfacl -m u:act:r file_name

where,
The -m (--modify) the permission
u -user name
r -read permission

Getting Access view
===================
getfacl file_name

Removing ACL Permission to a file
====================================
setfacl -b filename

For more reference please visit the following links.

http://gd.tuwien.ac.at/linuxcommand.org/man_pages/setfacl1.html
http://linux.about.com/library/cmd/blcmdl5_acl.htm
http://linux.about.com/library/cmd/blcmdl1_setfacl.htm
http://www.symantec.com/connect/articles/introduction-linux-capabilities-and-acls
http://www.sysadmindayph.com/blog/getfacl-and-setfacl-unix-access-control-acl-tool/