This is lowercase `P'. This is the same as the print command. See print.
Note for users of 1.8.9 MULTI: The `p' command in 1.8.9 version would print the line you were on in non-GUI mode. The current `p' command does not do that any more. To get the functionality of the 1.8.9 version of the `p' command, use the printline command. See printline.