What is the use of formatting pane in Tableau?

A pane that contains formatting settings that control the entire worksheet, as well as individual fields in the view.

You can format settings for fonts, alignment, shading, borders, lines and tooltips at the worksheet level. for instance, you may need to get rid of all the borders in a very text table or add shading to each different column in a very read.
When you add continuous fields to the view, Tableau creates an axis. The axis is labeled with a header.

To hide or show field labels, select Analysis > Table Layout > Show Field Labels for Rows or Show Field Labels for Columns.