The 9 in the image you post is the name of the file field for that binding group, each file upload behavior will have it's own binding group with the file field name in parenthesis.
in the image uplaod, you have set it to create 2 copies of the image, one using the [FileName] for the name, the other using [FileName]_thumb for the name.
the [fileName] binding is for the large image, the [FileName]_thumb binding is for the resized image you are createing