It might be helpful to clarify which book you mean, as 'The Princess and the Kiss' is a specific children's picture book by Jennie Bishop, not a novel. It’s a Christian allegory about purity, where a princess guards a special kiss given to her at birth, symbolizing her gift of love, and learns to value it instead of giving it away to unworthy suitors. The plot is a simple moral tale for young kids, often used as a gift for daughters.
I read it once as a kid and honestly found it pretty heavy-handed, even then. The metaphor is extremely literal, and the whole 'guard your gift' thing is presented as the princess’s primary purpose. It’s a product of a very specific kind of evangelical family media from the late 90s/early 2000s. If you're looking for a fantasy princess adventure, this definitely isn’t it.