It shows:

• PageName -- the title, the unique name of the page
• PageSize -- the technical size of the page, given by the number of characters (bytes) needed to store the text.
• EditHelpText -- a help text showing the markups most often used

• TextInputField -- a multiline text input area where the page content can be written and edited.
• SaveButton -- for storing the current state.
• SummaryInputField -- a single line input field for a summary that shows in RecentChanges
• MinorEditsCheckbox -- a checkbox that a user can select if he field that his changes need no attention from the readers, see MinorEdits
• PreviewButton -- for displaying the current state of the edited text without actually storing it at the server
• LastAuthorTextLink -- a link which displays the text version