How does the "Show only field name as column header"option work?

When you create a report, each column will show the field name and the metric name as the header.

For example, if you are creating a report using order metric, then the columns will show the field name and "Order" metric as the header:

Now, for the "Show only field name as column header", If you select "Yes" then the columns will show only the field name as the header.

If you select "No", then the columns will show the field name and the metric name as the header.