When using the term dedicated IP, we are referencing the difference of a shared IP and a dedicated IP address.
Shared IP Address:
A shared IP is used by several other servers alongside each other. This means that your users have the potential of bumping into the other server and attacks directed at another service on your IP may affect your service. This also often means you have a non-standard port for your game server. This is often confusing for many users when trying to setup DNS.
Dedicated IP Address:
A dedicated IP is assigned to one customer for one service. This keeps our customers isolated from one another and ensures the standard port for game servers are used. We assign this by default at no additional charge to our customers.