It gives you information about local and remote users.
finger [- s l m p] username
If you type in the command fingerturing, You will be presented with information about the user such as
Login name: turing real life: Alan Turing Directory: /home/turing Shell: /bin/bash Last login Wed Sep 6 16:07 on pts/12 from the.afterlife.nirvana.com New mail received Wed Sep 6 16:55:41 1965; unread since Wed Sep 6 16:08:22 1965 No Plan.To find out information on a remote user you can type finger and username followed by an @domain name For example to find out information on a user on a remote system one might type: finger> ghopper@djlocker.navy.mil
To find out more information check your local man pages.