What Does The Last Line Do

Hi, can some one tell me what the last line of code does: add_filter( ‘login_redirect’, ‘redirect_user_to’, 10, 3 );

<?php

// add this to the bottom of the functions.php file in yourt theme directory

function redirect_user_to( $redirect_to, $user ) {
	global $user;

	if ( $user->user_login == 'member' ) {
		$redirect_to = '/'; // redirect to home page
		return $redirect_to;
	}

	return $redirect_to;
}
add_filter( 'login_redirect', 'redirect_user_to', 10, 3 );

?>