Use the pmpro_discountcodes_extra_cols_body and pmpro_discountcodes_extra_cols_header hooks to add extra columns  to the discount codes page. This hook accepts the body HTML code of the extra column.

do_action("pmpro_discountcodes_extra_cols_body", string $code);

Parameters

$code

string

Source

File: https://github.com/strangerstudios/paid-memberships-pro/blob/master/adminpages/discountcodes.php