Here you can see a list of issues of the currently edited newsletters. The list contains information about when the issue was sent, how many e-mails of the issue have already been sent to subscribers and how many of them unsubscribed after receiving the issue.
You can manage the items in the list using the appropriate icon on the left side - edit () and delete (). New issues can be created by using the Create new issue link.
If there is a large amount of displayed newsletter issues, you can filter them by their subject using the filter above the list.
More resources can be found at Developer's Guide -> Modules -> Newsletters -> Overview.