Placing discrete fields on the rows and column shelves creates headers in the view that display the members of the field. For example, if you place a field containing products on the rows shelf, each product name is shown as row headers. In addition to showing these headers, you can show field labels, which are labels for the headers. In this example, the rows are labeled Department, thus indicating that the discrete department names are members of the Department field.
Field labels apply only to discrete fields. When you add continuous fields to the view, Tableau creates an axis. The axis is labeled with a header.
By default, field labels are shown. You can hide or show field labels at anytime by selecting or Show Field Labels for Columns.
You can format the fonts, alignment, shading, and separators for field labels.