This page allows you to change the start/end times for the listing, and it allows you to add or remove "listing extras". If this is an auction, it will also allow you to "clear all bids", and change the minimum bid amount, reserve, buy now price, etc. depending on what type of auction it is.

At the bottom of the page are several useful links, one to view the listing you are currently affecting, one to view the user's info, and one to send a message to the user (handy to easily send a message to the user informing them of the change to their listing).