Hello,
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The file that contains all labels options is basel/inc/third-party/nav-menu-images/inc/walker.php. Find the following code and add your own labels
<option value="hot" <?php selected( $label, 'hot', true); ?>><?php _e('Hot', 'basel'); ?></option>
<option value="sale" <?php selected( $label, 'sale', true); ?>><?php _e('Sale', 'basel'); ?></option>
<option value="new" <?php selected( $label, 'new', true); ?>><?php _e('New', 'basel'); ?></option>Regards
XTemos