The checkbox Enumerate all to the right is used to rename of all the columns which lie to the right of the selected column. For example, if the name of the selected column is "xyz", then the selected column and all of the following columns will be renamed to "xyz1", "xyz2", and so on.
The "<<" and ">>" buttons change the selected column. The highlighting of the column in the table behind the dialog box will change indicating that a new column has been selected. The column to which the formatting commands are applied is the one whose name appears in the "Column Name" box.
The Plot Designation selector is used to define which columns are to be used as X, Y or Z values or as error bars. In a table you can select several columns as X, in which case the column labels will display as [X1], [X2], etc. Multiple Y columns will display as [Y1], [Y2], etc. The same scheme is followed for multiple Z columns.
The Comment box allows entering text that will be displayed in the table header just below the column name when the Display Comments in Header option is checked.