Typically, this is where you configure particular game server settings. There are more options for some eggs than others.
This is also where you would need to change the Steam Query port for Steam-based (SteamCMD) servers, to the one you designated in "Additional Allocation(s)".
But for this Minecraft server, there are very few options in the setup panel itself.
You can change the:
Minecraft Version
Server Jar File
Download Path if you want to download a different server.jar