Okay, so you know how when you're learning something new, you might make some mistakes and get some things wrong at first? But as you learn more and more, you get better at it and start making fewer mistakes. Well, the infallibility of the church is kind of like that, but instead of just one person learning, it's a whole group of people who have been studying and teaching about God and the Bible for a really long time.
The infallibility of the church means that when the leaders of the church (like the Pope, for example) make a statement about a topic related to faith and morals, they can't be wrong. That's because they have been studying the Bible and the teachings of the church for a really long time, and they pray and reflect to make sure they are making the right decision.
Now, just because the church is infallible in matters of faith and morals doesn't mean that everything they do is perfect or that they never make mistakes. But when the church makes an official statement about something, we can trust that it is true and guiding us towards what is right and good. And that's a good thing, because it helps us learn how to be better people and follow God's will in our lives.