What does it mean to have a ladybird on your car window?
It means you have a ladybird on your car window.
It could mean that someone have (accidently or intentionally) put chicked bones on your car window. Probably you have parked the car near a fried chicken outlet. Also there is a possibility that a chicken was died or killed on your car window and only now you have noticed. Anyway, don't tuch those bones if you think it would be a bad thing, just put them away with a stick and wash.
A ladybird in English is also known as a ladybug or ladybeetle, a small red spotted beetle best known from the child's rhyme "Ladybird, ladybird, fly away home." In Shakespeare's Romeo and Juliet it is used by the nurse as a term of endearment. It was used in a similar way in Jonson's Cynthia's Revels, written shortly after.
The most common species of ladybird in Britain is the seven-spot ladybird. This bright red ladybird has seven spots and is thought to have inspired the name ladybird: "Lady" referring to the Virgin Mary (Our lady) who in early paintings is seen wearing a red cloak; the seven spots are symbolic of the seven joys and seven sorrows of Mary.