What does carrot-top mean?

"Carrot-top" is an informal term used to refer to a person with red hair, typically on the lighter end of the red hair spectrum. The term derives from the fact that carrots are commonly orange in color, and "carrot-top" is a way of comparing someone's hair color to the orange color of a carrot. It can be used playfully, but may also be perceived as a somewhat derogatory or teasing term depending on the context and how it is used.