Okay, so you know there are different kinds of churches and they sometimes have different beliefs and ways of doing things, right? Well, the ecumenical movement is when those different churches try to come together and work together, even though they may have some differences.
It's kind of like when you and your friend have different favorite colors, but you still want to play together and find things you both like to do.
The ecumenical movement started a long time ago when some people thought it would be good for different churches to talk to each other and try to find common ground. They wanted to work together to help people and make the world a better place.
Nowadays, lots of churches take part in the ecumenical movement. They might have meetings where they talk about their beliefs and try to understand each other better. They might also work together on projects like helping people who are hungry or building houses for people who don't have them.
So, the ecumenical movement is when different churches try to be friends and work together, even if they don't agree on everything.