The project closeout meeting (also called the project closeout review meeting) is usually attended by the project manager, the project team, and the project sponsor. The meeting may include some stakeholders. The project closeout meeting happens during the first step of the project closure.
The main point of this meeting is to make sure that all the deliverables are done, and to make the client sign on the acceptance document asserting that all the deliverables are indeed done and according to his requirements. The client may note on the acceptance document (also called the project closeout document) that some deliverables are missing or do not satisfy the objectives (The client may still sign and accept the project, but the team has to work on these issues before the final delivery of the project).
The acceptance document is just a small document containing all the project objectives, and below each and every objective, containing all the deliverables for that objective.
At the end of the document there is a place for the date and for the client's signature (where the client signs if he accepts the project).