KPO (radio station), a San Francisco radio station now broadcasting under the call sign KNBR
Communist Party of Austria (German: Kommunistische Partei Österreichs, KPÖ)
Communist Party of Germany (Opposition) (German: Kommunistische Partei Deutschlands (Opposition))
Knowledge process outsourcing
Ku-ring-gai Philharmonic Orchestra, of Australia
Pohang Airport Pohang, South Korea
Karachaganak Petroleum Operating, operator of the Karachaganak Field
That's what Wikipedia throws out.
"KPO Minecraft" throws out nothing more elaborating, so either ask "them" like Leestons said, or simply assume it's a clantag or something.