Okay, let's pretend we are at church. When the priest leads the worship service, he reads from a special book that is different from the regular Bible. This book is called a liturgical book and it has a lot of important information about how the worship service should go.
For example, it tells the priest what prayers to say and when to say them. It also has instructions on when to stand, when to sit, and when to kneel. The liturgical book of the Roman Rite is the special book used in Catholic churches all over the world.
The liturgical book has been around for a very long time, and it is always being updated or revised. This is so that everyone can understand what the priest is saying, and so that the service will flow smoothly.
So, in short, a liturgical book is a special book used during Catholic church services that has important information about how the service should go. The liturgical book of the Roman Rite is used in Catholic churches all over the world and is always being updated to make sure everyone knows what is going on.