Okay kiddo, so an apostolate is a fancy word for an organized group of people who work together to spread or teach the ideas of their religion or belief system.
Think of it like a club at school. Let's say there's a club that really loves plants and they want to teach other people about how to take care of them. They might have meetings where they share information and tips, and they might even go out to events like Earth Day to spread their love of plants to others.
In the same way, an apostolate is a group of people who want to share their religious ideas with others. They might go door-to-door to hand out religious pamphlets, or they might organize events to teach others about their beliefs. It's all about sharing and spreading the word.
Some apostolates are connected to specific religious orders or communities, while others might be more informal groups of friends or family members who share a common belief. But no matter what, the main goal is always to share what they believe and help others learn about it too.