Job Description
PAs should be capable of competently managing the office in their manager’s absence. They should be confident enough to delegate upwards to their manager's direct reports in order to effectively manage their manager's time and workload. Maintaining confidentiality is a fundamental requirement for PAs because ultimately, building a strategic relationship with their manager is only possible if their manager trusts them enough to keep them in the loop about what is going on in the business. 
UNDERSTANDING PA DUTIES
Corporate Personal Assistant positions demand competence and skill in the following areas:

Reading, monitoring and responding to the manager's email,
Answering calls and liaising with clients competently,
Preliminary drafting of correspondence on the manager's behalf,
Delegating work in the manager's absence,
Diary management
Planning and organising meetings,
Organising complex travel,
Taking action points and writing minutes,
Preparing papers for meetings,
Taking dictation,
Planning and organising events,
Improving office systems
Conducting research,
Preparing presentations,
Managing and reviewing filing and office systems,
Typing,
Sourcing and ordering stationery and office equipment,
Managing ad hoc projects