A "forum with a landing page" refers to an online forum that has a dedicated, single webpage designed to capture visitor attention and encourage specific actions, like signing up for the forum, before directing them to the full forum interface; essentially, a focused entry point to the forum community with a clear call-to-action. 
Also found this from XF 

[URL unfurl="true"]https://xenforo.com/community/threads/landing-page-help.186944/[/URL]
Landing PAge
[URL unfurl="true"]https://www.baysidegamers.com/[/URL]


i will try and get more examples.