This theme has both left or right sidebar but you can’t use them at the same time.
It wouldn’t be difficult to modify but it is way out of scope of free support.
The basic idea is to:
– Register new widget area
– Create a new sidebar file called sidebar-left.php
– Then call it the same way default sidebar is called in theme but this time you would have to use <?php get_sidebar( 'left' ); ?>
– Since this theme is Bootstrap based it would be easy to arrange columns. Default setup is 4+8 columns but you could adjust it to 3 + 6 + 3 or something like that.