If you are getting this error while shipping internationally via FedEx, this means that the description on your shipment’s first customs line item (you might get this for the second or third customs line as well) did not meet FedEx’s keyword criteria.
To fix this, you will need to first check this guideline provided by FedEx with acceptable commodity descriptions. Once you are familiar with this, you will need to go and edit your customs delcarations with more descriptive lines.
You can check some top tips on getting a better understanding on how to work with customs, directly on FedEx’s page here.