Yes. You can change the Speakers slug by following the steps below:
Don’t forget to take a back up of the file prior to any changes.
Open wp-content/themes/januas/lib/include/post-types.php via FTP or Cpanel
3) Search for the following line:
‘rewrite’ => array(‘slug’ => ‘speakers’)
4) Replace that line with the following
‘rewrite’ => array(‘slug’ => ‘exhibitors’)
5) Update the file.
6) Update the permalink structure ie via settings -> permalink menu