Column headers are gray-colored rows used to label each column or group of columns. By default, these headers are populated with letters in alphabetical order.
To reflect the type or category of data in a particular column, give it a custom name and then display it in a column header. For example, instead of letters as labels such as A, B, C, ... name them ID, Full name, Country, ....
More complex data structures can be displayed with multiple headers, each representing a different category of data. To learn more about nested headers, see the column groups page.