WordPress at a glance
function is not described

WP_Query::is_post_type_archive() WP 3.1.0

Is the query for an existing post type archive page?

This is a method of the class: WP_Query

No Hooks.

Return

true/false.

Usage

$WP_Query = new WP_Query();
$var = $WP_Query->is_post_type_archive( $post_types );
$post_types(mixed)
Post type or array of posts types to check against.
Default: ''

Code of WP Query::is post type archive: wp-includes/class-wp-query.php WP 5.2

<?php
public function is_post_type_archive( $post_types = '' ) {
	if ( empty( $post_types ) || ! $this->is_post_type_archive ) {
		return (bool) $this->is_post_type_archive;
	}

	$post_type = $this->get( 'post_type' );
	if ( is_array( $post_type ) ) {
		$post_type = reset( $post_type );
	}
	$post_type_object = get_post_type_object( $post_type );

	return in_array( $post_type_object->name, (array) $post_types );
}