Hey there kiddo, do you know what a book is? It's like a bunch of papers put together and usually it tells you a story or teaches you something. Well, a "livre d'art" is a book specifically about art.
Inside this book, you will find beautiful paintings, sculptures, and other kinds of art that people have made throughout history. These artworks are usually accompanied by other pieces of information that help you understand them better like who made them, where they come from, and what they mean.
In some "livres d'art," there are even little activities you can do to help you learn more about the art. For example, you might be asked to draw your own version of a painting or look for certain details in a sculpture.
So basically, a "livre d'art" is a book that teaches you all about art and its amazing history. It's a great way to learn and appreciate beautiful things that people have created!