Get a WordPress menu from a specific menu location

functions.php

<?php

/**
 * Returns the menu object associated with a particular menu location.
 *
 * You could then get the slug of the menu, for example, via 
 * $menu_object->slug (or whatever variable you saved the menu object as).
 *
 * @param string $location_slug
 *
 * @return object
 */
function get_menu_from_location( $location_slug ) {
  return get_term( get_nav_menu_locations()[$location_slug], 'nav_menu' );
}