I really love middle-grade. Middle-grade books have a little more of a magical, light-hearted feel. You can be a little bit more quirky, you can have a little more humor. It doesn't get so dark and deep.

This quote is talking about middle-grade books, books that are usually targeted at 8 to 12-year-olds. The quote is saying that these books often have a magical or light-hearted feel to them. The author suggests that they can be quite humorous, without getting too deep or dark. In other words, they can discuss serious topics without getting bogged down in sadness or despair.