This area of the dialog box is for viewing the files you have selected for copying. It contains the following items:

This list displays the truncated path(s) of the file(s) to be copied. As entries are being copied, they are highlighted. After a file is copied, it is removed from the list. If an error occurs during the copying process, the copy is aborted and the list displays the names of files that have not yet been copied.

Pressing this button removes the selected files/directories from the Source Files/Directories List.