For those working on EC services who searched “What is PO?” PO is an abbreviation for Purchase Order, a technical term referring to purchase orders, order forms, purchase instructions, etc.

• Purchase order - Wikipedia

《purchase order》購入注文。商品名・出荷条件などの販売条件を明記した正式の注文書。 "Purchase order: A formal order form that clearly states sales conditions such as product names and shipping conditions."

ピーオー【PO】［purchase order］の意味 - goo国語辞書

PO（purchase order）とは、商品名や出荷条件などの販売条件を記載した発注書（注文書、購買指示書など）のことである。その他にはPOを発行する(issue a PO)や、POを取り消す(cancel a PO)などがあり、英語圏で一般的に使われる表現である。

“PO (purchase order) refers to a purchase order (order form, purchase instruction, etc.) that contains sales conditions such as product names and shipping conditions. Other expressions include issuing a PO (issue a PO) and canceling a PO (cancel a PO), which are commonly used expressions in English-speaking countries.”

PO（ピーオー）とは | BtoB・マーケティング用語集

By the way, besides Purchase Order, Product Owner and Project Owner are also sometimes abbreviated as “PO.”

When using it in the workplace, there’s the problem that you can’t understand the meaning of PO without context, so I try to avoid using abbreviations as much as possible.

That’s all from the Gemba.