The General Assembly (GA) is probably the main organ of the United Nations, and is the one in charge of approving the resolutions debated by the Committees. During the Opening Ceremony, the GA allows the ambassadors to have a brief speech to public declare their intentions and positions on the main issues on the agenda. On the last day, each Committee will bring a resolution to the attention of the GA members, that will have to debate once more and decide if the resolutions are good or not. If a resolutions passes in the GA, it becomes reality.
The President of the General Assembly is the second high person of the Secretariat after the Secretary General. She is in charge of all the debating procedures and delegates' responsibilities inside the Committees. She is an highly experienced chair and runs the debates the first and the last days. The PGA is the only person allowed to overrule the Rules of Procedures of the conference if needed.