bazilazi

I do not know how to thank you 🙂
I understand now how it works.

if(!dynamic_sidebar('footer') // if not exist dynamic sidebar named id footer (or something like that)
// display static text
endif;

I changed this code to

<?php if ( is_active_sidebar('footer') ) : ?> //check if sidebar's active
    <?php dynamic_sidebar( 'footer' ); ?> //if yes display it
<?php endif; ?>

Thank you very much! 🙂