"Reach out" refers to a charity program that aims to help people who are in need. Imagine you have a lot of toys, but there's a kid in your class who doesn't have any toys at all. If you decide to give some of your toys to that kid so they can play too, you are "reaching out" to help them.
Similarly, non-profit organizations have programs that reach out to people in need. For example, if someone doesn't have enough food, the non-profit organization might "reach out" to them by providing them with meals so they don't have to go hungry.
It's all about being kind and helping those who need it. So, when you hear about a group that is "reaching out," it means they are trying to help make the world a better place by helping others.