Approvals are a way of gauging the approval of one or many users on the workflow. They can have a list of configurable statuses such as Approved, Declined, Changes Requested etc. They can also be configured to allow approval on behalf of someone else (useful if that person does not have access to the system).
As the project progresses, users can track approvals from within the approvals tab. This section gives an overview of all the approvals that are currently awaiting review, have been commented on or have been approved.