WordPress displays different information about posts, pages, users and other content in a vertical format in each of the above screens, called columns. Visibility of each column can be toggled in the Screen Options.
To display extra information about contents such as posts and users, WordPress uses columns to organize and present information.
WordPress itself has some default columns (such as categories and tags in the post screen), but columns can also be added via a plugin or a theme's "functions.php" file. These custom columns add extra information to their related screens.
Below is a screenshot of the default columns, belonging to the "All posts" screen:
Visibility of these columns can be toggled in the "Screen Options", located under the admin bar. Below is an screenshot of the above page's screen options:
WordPress can sort the lists by column's value. To sort a list by the value of a specific column, click on the column's title. Clicking on the column again will reverse the sorting, from ascending to descending, or vice versa.