The article discusses how the European Union works together on trade and customs laws. It explains how countries in the EU cooperate to make sure goods can move freely between them. The researchers talk about getting rid of taxes and limits on how much of a product can be brought in. They also mention how the EU deals with unfair treatment of goods from different countries. The article covers the rules for bringing goods into and out of the EU, as well as how the EU handles trade with other countries.