open but with no customers; open for business but idle
Describes a shop or business that is officially open but has virtually no customers. Often used figuratively for any situation where the form exists but there is no real activity.
平日の午前中は開店休業の状態だ。
On weekday mornings, the shop is open but has no customers.
新しいサービスを始めたが、今のところ開店休業だ。
We launched a new service, but for now it's like being open with no business.