When an order is confirmed in the CRM it is put into a status of waiting to be confirmed. Orders in this status are then picked up to be confirmed into the ERP or Accounts System. Depending on the type of integration this may be done instantly or in batches on a schedule. The Processing status on an order means that this order has been picked up to be confirmed into your ERP system and should arrive shortly.
If an order has been in this status for over an hour it is possible that the order confirmation batch or process that picked this order up is not working as expected and should be investigated. More information on how to manage your on-premise imports can be found here.
If you are confident that the order confirmation should be retried for the order you can press the retry button. This will put the order back into waiting to be confirmed ready for the next batch or process to pick it up.