Some aspects of the work area on your dashboard are by default hidden to prevent cluttering and avoid confusing the novice user. These include the author metabox on posts, the slug metabox on pages and many more.
To modify what appears when editing a post, a page, a custom post type or the menu page you can use Screen Options. Screen options appear as a hanging tab at the top right hand side of your dashboard window
clicking the tab will display the available options
In general you won’t be using screen options very much, but they do come in handy in certain cases. Let’s take our very popular Santorini Resort theme, the theme features listing pages which display your rooms, however this listing page displays all rooms, what happens if you just want to display one room category? That’s where screen options come in, you navigate to Appearance > Menus and click screen options, you’ll notice that there is a checkbox with the label Room Categories
check it and you will get a new list of menu items which you can add to your menu and create pages that will only display a particular room category.