Since a piece of art amounts to saying "this is important", and re-creates reality, the art will convey something called metaphysical value-judgments. These aren't ordinary values or value-judgment. They're evaluations of the world itself, and how compatible it is with human flourishing. They're judgments about the nature of life, and whether it's good or bad.
Metaphysical value-judgments are answers to fundamental evaluative questions about the world. Here are some examples. Is the world knowable? Are we fit for survival? Are men good or evil by nature? Do we have the ability to choose? Is happiness attainable? Can we make plans for the future? Is there a supernatural being who controls us by whim? Do we have the power to set the course for our lives?
These kinds of questions are not just factual questions. They ask about things that have a significant impact on our lives. They ask about the elements that make the world suitable for living in.
These metaphysical value-judgments are an important part of the art work. If the art re-creates reality, the metaphysical value-judgments say what kind of world it is. It goes beyond simply showing the world. It conveys an evaluation of the world. But it does so by embedding the evaluation into the view of the world itself. The world that's shown in the art is built around the evaluation.
Let's take some examples, recognizing that evaluating art is fairly complex and I'm simplifying things. Now if the artist conveys a world full of misery and suffering, he's showing that he believe that is the nature of life. The art doesn't just have someone offering their appraisal of it as full of suffering or misery. The actual world shown by the art is full of it. The metaphysical value-judgment determines the way the art is conveyed.
Ayn Rand talked about naturalistic literature, which aims to convey the world "as it is", instead of how it should be. The intent is to create believable characters we are likely to meet in real life. The characters end up flawed, ignorant, lowest common-denominator, etc. The events in their lives are dull and pointless. When something interesting happens in the book, it happens to the characters, not because of them. The general impression is a lowly world where heroes and greatness is impossible, where people don't control their own lives or try to make anything of them.
When metaphysical value-judgments are conveyed, you can see how this can help concretize normative abstractions, as we mentioned earlier. The art can go beyond conveying what the world is, and instead create a view of what the world should be like. In this way, art can convey a moral ideal. It can show us what our lives should be like, and act as a beacon to guide our own choices.