It's a widget in sidebar.

On your website or this forum too, the forum page has full width

Please edit forum page and check the Page Template section in admin screen. Or maybe your theme has additional options for page layout. So try to find some option to set "Full Width". This is a not wpForo option, this should be set through Page settings.

And to the right of this page there is recent replies, not for me

As far as I see you didn't read FAQ section of wpForo plugin, this is the second question which has answer here: https://wordpress.org/plugins/wpforo/faq/ . wpForo has "Recent Posts" widget in Dashboard > Appearance > Widgets admin page. Just put it in the sidebar which is being used on forum page. There is a sidebar called "wpForo Sidebar", don't use this if your page has already a sidebar, you the one which is used on all pages.

yep thank you Glados and Robert.

I just find this information, shame on me 😉