The office of regulatory affairs is like a big group of people who help make sure that things are safe for us to use. Just like how your parents might check that your toys aren't broken or have any sharp edges, the office of regulatory affairs helps check that food, medicine, and other things we use don't have anything dangerous in them.
They make sure that the companies that make these things are following all the rules and laws that are in place to keep us safe. They also check that the things we use are doing what they are supposed to do, and that they aren't making any false claims about what they can do.
Basically, the office of regulatory affairs is like our big safety helper, making sure everything is safe for us to use.