WordPress at a glance
action is not described

woocommerce_admin_field_(type) action-hook . WC 1.0

Default: run an action.

Usage

add_action( 'woocommerce_admin_field_(type)', 'action_function_name_5081' );
function action_function_name_5081( $value ){
	// action...
}
$value
-

Where the hook is called

WC_Admin_Settings::output_fields()
woocommerce_admin_field_(type)
woocommerce/includes/admin/class-wc-admin-settings.php 679
do_action( 'woocommerce_admin_field_' . $value['type'], $value );

Where in WP core the hook is used WooCommerce

woocommerce/includes/admin/settings/class-wc-settings-emails.php 27
add_action( 'woocommerce_admin_field_email_notification', array( $this, 'email_notification_setting' ) );
woocommerce/includes/admin/settings/class-wc-settings-payment-gateways.php 26
add_action( 'woocommerce_admin_field_payment_gateways', array( $this, 'payment_gateways_setting' ) );