What that section is trying to show is how you can have your infobox display a fallback value. In this example, the "source" is "women". Typically, this means that the infobox will display the row (the provided value and label (if specified using the label tags)) if the parameter "women" has been assigned a non-whitespace value; otherwise, the row will be omitted. Let's say, however, that if "women" is not specified, you want to copy the value from parameter "ladies"; and if that was not specified, you want to display "Janedoe". That is what the section is showing you how to do.