Specifying Header Content Type
Overview
By default, the column headers display letters and the row headers display numbers. You can customize the column headers to display numbers or the row headers to display letters. You can also have the headers appear blank.
If your sheet displays multiple column or row headers, you can specify where the automatically provided text or blank row appears. By default, it appears in the bottom-most row of column headers and the right-most column of row headers.
If you want the headers to display custom text, see Specifying Header Text.