The United Nations (UN) made some rules for moving things that can be dangerous, like chemicals or explosives, from one place to another. These rules are called the UN Recommendations on the Transport of Dangerous Goods.
The UN made these rules so that everyone would be safe when moving dangerous things around. The rules tell people how to pack the dangerous things, what kind of containers to put them in, and how to label and handle them.
To make sure that everything is done right, there are special people who are trained to follow the rules. They are called "dangerous goods safety advisors" (DGSAs). They make sure that the people moving the dangerous things follow the rules so they don't get hurt or cause anyone else to get hurt.
The UN recommendations are very important because moving dangerous things can be very dangerous if it's not done correctly! By following the rules, everyone can be safer.