URL that contains the web-based sign-in page for this application. If the application is configured to perform service provider-initiated ...

URL that contains the web-based sign-in page for this application. If the application is configured to perform service provider-initiated single sign on, then when a user navigates to this url, the service provider will do the neccessary redirections to authenticate and log on the user in the application.

For example when a user navigates to my apps portal and clicks on the application tile, they will be redirected to the url configured as Sign On Url.