The International Radiation Protection Association (IRPA) is a big group of people who work together to help make sure that everyone stays safe from things that can be harmful for us called radiation. They do things like studying the ways that we come into contact with radiation, how we can protect ourselves from it, and what can happen to us if we are exposed to too much of it.
Think of it kind of like a bunch of superheroes who work together to make sure that we are safe from things we can't always see or feel, and to help the people who can get hurt by them. They talk to each other and share ideas and research, and they also work with governments and other organizations to make sure that laws and regulations are in place to help protect us from radiation.
So basically, the International Radiation Protection Association is a group of really smart and caring people who want to keep us all safe from radiation and make the world a better place!