Adding an extra sidebar to your theme

get_sidebar('left'); actually refers to a file, not the sidebar itself.

1. Are you seeing the sidebar in the Admin section?
2. Are you trying to display it on the front end?

If the answer to both of these questions are “yes”, then here’s the solution:

Create a file called sidebar-left.php. In this file, you will need to add your rendered HTML, something like this:

<?php
// Left Sidebar template
?>
<div id="left-sidebar" class="sidebar">
    <?php dynamic_sidebar( 'sidebar-left' ); ?>
</div>