Okay kiddo, so you know how when we go to church, different churches can have different ways of doing things? Like some people stand up to sing and some people sit down? Well, the ambrosian rite is one of those different ways of doing things.
It's named after a man named Ambrose who was a really important bishop in Milan a very long time ago. He helped create the way of doing things in church that we now call the ambrosian rite.
So what's different about it? Well, for one thing, instead of just using regular bread for communion, they use something called "azymes" which are basically unleavened wafers made from just flour and water. They also have different prayers and songs and ways of doing things during the church service than some other churches do.
But even though it's different, it's still a valid way of worshiping God and lots of people in Milan still use the ambrosian rite to this day. It's just like how different families have different ways of doing things but they're still all part of the same family. Pretty cool, huh?