get_the_archive_description.php

<?php
/**
 * Retrieve category, tag, or term description.
 *
 * @since 4.1.0
 *
 * @return string Archive description.
 */
function get_the_archive_description() {
	$description = '';
	if ( is_post_type_archive() ) {
		$description = post_type_archive_description( '', false );
	} else {
		$description = term_description();
	}

	/**
	 * Filter the archive description.
	 *
	 * @since 4.1.0
	 *
	 * @see term_description()
	 * @see post_type_archive_description();
	 *
	 * @param string $description Archive description to be displayed.
	 */
	return apply_filters( 'get_the_archive_description', $description );
}