How can I change the scale value?

In Realteo Options → General Options you can select the scale symbol that will be used with properties. The defaults are ‘sq m’, ‘m² and ‘sq ft’.

In case you want to change it to something that is not available in options, you can do it by simple filter that you should add to you child theme functions.php.

add_filter('realteo_scale','my_custom_scale_symbol');
     function my_custom_scale_symbol(){
     return 'symbol';
 }