Adding ip to netcup vms

Trying to configure an additional IP that is a redirect. I have no idea where to start and looking all of the answers it is confusing me more than when I started. Looking at the help from netcup it says to use a redirect but I have never heard that term before. Is it a bridge? to I need to set ip forward? Please help network gurus. Just starting to learn nixos so i am severely handicapped.

What do you try to achieve with this?