WordPress at a glance
function is not described

wpdb::__get() public WP 3.5.0

Makes private properties readable for backward compatibility.

It's a method of the class: wpdb{}

No Hooks.

Return

Mixed. The private member.

Usage

$wpdb = new wpdb();
$wpdb->__get( $name );
$name(string) (required)
The private member to get, and optionally process.

Changelog

Since 3.5.0 Introduced.

Code of wpdb::__get() WP 5.5.1

<?php
public function __get( $name ) {
	if ( 'col_info' === $name ) {
		$this->load_col_info();
	}

	return $this->$name;
}