You can define which toolbars are visible by selecting Menu > Options in the top right corner.
The Menu Bar is the File, Edit, View, etc., menu usually visible at the top of a window. All those options can be accessed through the Menu icon. The Mail Toolbar contains, for example, the Get Mail, Write and Quick Filter options.
Quick Filter Bar is the search field above the message listing. It enables a quick search in the open e-mail folder. After writing a search word or a part of it, you can specify the search to include the sender, receiver or title field or the entire content of the e-mail.
Status Bar is the bar in the bottom of the window, showing the quota status of the mailbox, number of unread e-mails (or the number of selected messages) and the total amount of messages in the folder.