MY AIM IS USE TO REMOVE PORT FROM URL AND ACCESS MY FORUM BY www.sample.com/forum
For that I found this link on official site (https://docs.nodebb.org/configuring/proxies/apache/)
The next step is creating a configuration file, typically named after your site (e.g. www.example.com.conf), in the Apache vhost config directory, usually found at /etc/apache2/sites-available/. Make sure to match server name to the URL field defined in the config.json.
I don't understand Configuration part of the above mentioned link