WordPress at a glance
function is not described

_wp_nav_menu_meta_box_object() WP 3.0.0

Adds custom arguments to some of the meta box object types.

No Hooks.

Return

Object. The post type of taxonomy object.

Usage

_wp_nav_menu_meta_box_object( $object );
$object(object)
The post type or taxonomy meta-object.
Default: null

Code of wp nav menu meta box object: wp-admin/includes/nav-menu.php VER 5.0.3

<?php
function _wp_nav_menu_meta_box_object( $object = null ) {
	if ( isset( $object->name ) ) {

		if ( 'page' == $object->name ) {
			$object->_default_query = array(
				'orderby' => 'menu_order title',
				'post_status' => 'publish',
			);

		// Posts should show only published items.
		} elseif ( 'post' == $object->name ) {
			$object->_default_query = array(
				'post_status' => 'publish',
			);

		// Categories should be in reverse chronological order.
		} elseif ( 'category' == $object->name ) {
			$object->_default_query = array(
				'orderby' => 'id',
				'order' => 'DESC',
			);

		// Custom post types should show only published items.
		} else {
			$object->_default_query = array(
				'post_status' => 'publish',
			);
		}
	}

	return $object;
}