Labelling rules typically require, at minimum, the product name, country of origin, net quantity, and for certain goods, ingredients, safety warnings, expiry dates and care instructions. Many countries require this information in an official language, sometimes in more than one, and in specific units of measurement.
It is far cheaper to have your supplier apply the correct labels before the goods ship than to relabel a container after arrival, and in some countries relabelling after arrival is not permitted at all. Send your supplier a written labelling specification with your purchase order, not after.