A pfSense firewall is a good and inexpensive solution to secure your network. For example, you can allow public internet traffic from your servers to pass through the pfSense firewall and completely or partially close your public connection to your servers, so that they can no longer be attacked via the internet.
There are two relatively simple options for passing traffic through your pfSense firewall: you can choose to have all traffic go through your firewall by using a VPN connection, or a part of the traffic, e.g. traffic that runs through a specific port, by using port forwarding.
Simply put, it's more convenient to use a VPN server if you're working with multiple servers, and port forwarding if you're using one or more servers and those servers don't use the same ports.
The following tutorials explain how to use both options: