WordPress at a glance
function is not described

get_theme_updates() WP 1.0

No Hooks.

Return

Array.

Usage

get_theme_updates();

Code of get theme updates: wp-admin/includes/update.php VER 5.0.3

<?php
function get_theme_updates() {
	$current = get_site_transient('update_themes');

	if ( ! isset( $current->response ) )
		return array();

	$update_themes = array();
	foreach ( $current->response as $stylesheet => $data ) {
		$update_themes[ $stylesheet ] = wp_get_theme( $stylesheet );
		$update_themes[ $stylesheet ]->update = $data;
	}

	return $update_themes;
}