What is the importance of "Set Activation date " in LIAM portal

From my understanding your are just deferring the change to that object to the date you set when clicking on set action date.

For example if I click on an employee in the Manager client and then assign them to an application role, once done instead of clicking on save I would click on object in the menu and then the option define execution time. If I set that to Monday September 3rd then this creates a deferred operation that will kick off on that date. You can see deferred operations within Manager by clicking on the menu Database and then Show deferred operations

Or did you mean the entry date?

i am referring to New user creation in One idm portal.While New User creation we have that option "set activation " date.Does it mean that when the activation date got reached ,the entire activation process will begin automatically.

i am referring to New user creation in One idm portal.While New User creation we have that option "set activation " date.Does it mean that when the activation date got reached ,the entire activation process will begin automatically.

What is that feature indicates 'set activation date".

You should share the version on OneIM you are using and a screenshot where the community can identify the flag you have mentioned. I was unable to locate it in my 8.0.1 test environment.

I am using LIAM 7.1 version.

In Portal,

the option is like this" Set Activation Date" and description like " setting the activation date will affect the date of the further processing  of the account activation".There is a check box and text field entry for giving future date 

Still, I am unable to find the option you are describing. That's why I asked for a screenshot.