Before you can begin selling a product in an EU country, it must comply with the rules that apply in that country and throughout the EU. Once the product has been approved for sale in one country, it can then in principle be sold anywhere in the EU. In practice, individual EU countries do retain the right, in certain cases, to restrict the access to their market of products already sold in another EU country.
Different rules must be followed at each step of the process of bringing a product to market.
Many products must be labeled if they are to be sold in the EU. There is mandatory and voluntary labeling.
On the portal Your Europe you can find out more about what you need to look out for.
The Your Europe Portal provides comprehensive information for citizens and businesses.
Your Europe Portal (European Commission)