In the classic fairytale of Snow White, there is no definitive age given for the titular character when she kisses the prince. However, the story suggests that Snow White is a young woman who has been forced to flee from her home and live in the forest due to the jealousy of her stepmother.

The fairytale of Snow White was originally recorded by the Brothers Grimm in the early 19th century. In their version of the story, Snow White is described as a young girl who is still a child when she is sent away by her stepmother. The story does not give a specific age for Snow White, but it is implied that she is quite young when she is forced to flee into the forest.
Later versions of the story, such as the popular 1937 Disney animated film, depict Snow White as a young woman in her late teens or early twenties. In this version of the story, Snow White meets and falls in love with the prince after he discovers her in the forest and awakens her from her enchanted sleep with a kiss.
The idea of a prince awakening Snow White with a kiss has been the subject of much discussion and debate over the years, with some critics arguing that it perpetuates harmful gender stereotypes and reinforces the idea that women need a man to rescue them. Others argue that the fairytale is a product of its time and should be viewed as a work of fiction rather than a guide to gender roles and relationships.
In conclusion, while there is no definitive age given for Snow White when she kisses the prince, the story suggests that she is a young woman who has been forced to flee from her home due to the jealousy of her stepmother. The age of Snow White has been depicted differently in various adaptations of the story, but the idea of a prince awakening her with a kiss remains a central element of the fairytale.