From b2evolution manual

Display message if there are no any posts.

[edit] Example

<?php   
   display_if_empty( array (
      'before'    => '<p class="msg_nothing">',
      'after'     => '</p>',
      'msg_empty' => 'Sorry, there is nothing to display...'
    ) );
?>

[edit] Parameters

[edit] Return value

This function return false, if there are no any posts.
If there are some posts then this function return true and displays content.