how do you understand this sudoers file????? help appreciated 

[sd952814@prh00768.lhsprod /var/fedex/mkacct/rules]$ cat rmas.sudoers
######################
# RMAS ADMIN SUDO RULES
######################

%rmascm         ALL = /bin/su - *rmasadm
%rmascm         ALL = /bin/su - /opt/VRTS/bin/hastatus -sum
[sd952814@prh00768.lhsprod /var/fedex/mkacct/rules]$ cat winds.sudoers
######################
# WINDS-APP ADMIN SUDO RULES
######################

%dbaag          ALL = /bin/su - oracle
%windscm        ALL = /bin/su - windsadm
%windscm        ALL = /bin/su - wxdist
%windscm        ALL = /bin/su - wxweb

 e.g. 

%dbaag          ALL = /bin/su - oracle

In your system there exists a group named 'dbaag" and a user id "oracle". 
Above statement says - allow any users that are member of group "dbaag" to switch to user "oracle" using command sudo su - oracle 

This enables the user run applications/commands that were only allowed for 'oracle' user (e.g. database realted).

For detail- check linux manual or some good tutorial.

 appreciate and what abt that     /bin/su     means?