The Video Bookmark Edit dialog is used to change the name of the video bookmark (and the time for an Image Sequence). It is opened from the Video Bookmarks Pane.
In this dialog you will see the video the bookmark is attached to (important for multi-video projects), the frame number in the video, and the time code for this bookmark. For new bookmarks the name defaults to “Bookmark [fn]” where fn is the frame number. You can edit the name as you wish. If you are working with an Image Sequence the top row says Image Sequence instead and you can enter the time of this particular bookmark for use in the speed calculations.