bbPress.org

use the bbpress stats widget or shortcode [bbp-stats] in a page

for just all topics it would placing these in a template.

these come the template content-statistics.php which you could copy into child theme into a folder called bbpress and customize.

<?php echo esc_html( $stats['topic_count'] ); ?>

for just replies it would be

<?php echo esc_html( $stats['reply_count'] ); ?>

@snecz

i gave you two shortcodes for each instead

place the two functions into your child themes functions.php or add the snippets to a functionality plugin.

[bbp-topic-stats]

function rk_bbp_topic_stats() {
    $stats = bbp_get_statistics();
    echo "<dl role='main'><dt>Topics</dt><dd><strong>";
    echo esc_html( $stats['topic_count'] );
    echo "</strong></dd></dl>";
}

add_shortcode('bbp-topic-stats', 'rk_bbp_topic_stats'); 

[bbp-reply-stats]

function rk_bbp_reply_stats() {
    $stats = bbp_get_statistics();
    echo "<dl role='main'><dt>Replies</dt><dd><strong>";
    echo esc_html( $stats['reply_count'] );
    echo "</strong></dd></dl>";
}

add_shortcode('bbp-reply-stats', 'rk_bbp_reply_stats');  

Thanks for the function. Is there a way to output the amount of replies of a specific topic?

Thank you for your help.

@newguy Take a look at the bbp_topic_reply_count() and bbp_get_topic_reply_count() functions.

bbpress just uses wordpress users, so this should get you what you want

https://www.wpbeginner.com/wp-tutorials/how-to-show-total-number-of-registered-users-in-wordpress/