Question

To be a good servant leader, putting themselves at the service of the Scrum Teams doing the work and challenging the organizational constraints which impede their progress.

Scrum is not a system.  It is a framework designed to help individual teams be more successful at delivering incremental value and adapting to change.  There are 3 responsibilities defined that are key to the success of the framework.  Notice I said responsibilities and not job descriptions. 

Executive secretary is not one of those responsibilities.  But even those outside of the 3 Scrum responsibilities have vested interests in the success of the Scrum Teams.  As @Ian points out, an Executive Secretary can provide service to the Scrum Teams in helping them to be self-managing, self-organizing.  The Executive Secretary can also provide a much needed service of helping to remove impediments that prevent the Scrum Teams from being successful.  Your access to the Executive levels of the organization can be invaluable to the Scrum Teams when they need some form of organizational support or change. 

Hello Pantea,

I cannot agree less with Daniel that Scrum is not a system rather Scrum is a Framework that is used to solve complex problems. There is no accountability in the Scrum  known as an Executive Secretary, rather there is the Product Owner, Scrum Master and Developers.

According to Barry Overeem in his white paper, there are 8 Stances of a Scrum Master, one of which has mentioned by Ian is a Servant Leader, probably your Scrum Master can wear the hat of an Executive Secretary or a Scribe during one of the Scrum ceremonies if he/she so desires.