When you’re logged in to your WordPress administration panel, the Screen Options tab is almost always displayed at the very top right of the screen. If you click it, you will be presented with display settings for the admin page you’re currently viewing. Which settings are displayed depends on which admin view you’re currently viewing.
If you’re editing a post or page, the Screen Options will allow you to select which boxes to display: Featured Image, Word Settings, Discussion, and so on. If you’re viewing the list of all pages or posts on your site, you can use it to show or hide different columns in the table and select how many items you want to display per page.
Which boxes that are available to be displayed and hidden depends on which boxes your theme and active plugins have support for. You can also choose whether to display the meta boxes on the edit screen in one column or two columns (the latter is default).