OAM provides the single-sign on and signle sign-off feature for the web applications.
1. Single Sign-on : If there are multiple applications in the enterprize organization where the user can login to any one of the application and access other related applications with out login-in.
E.g : We are familier with google applications like Gmail, Photos, Drive, Playstore, Google+, Youtube, etc.
These are different applications of google where they all share the single username and password to login.
We can login to any one of the applications and can access the remaining from the same browser with out re-login.
Even though they belongs to different applications / different software, programmming languages, hardware and deployed on different servers. They are accessed with single sign-on.
2. Single Sing-off: This is simillar to single sing-on, when we logout from any one of the the application logged in, the user will be logged out from other applications also. This is called single sing-off.
Oracle Access Manager provides the similar functionality for the web applications.