Generally speaking we would expect the term '24MY' to refer to the fact that the car is a 2024 model year, in other words it is the latest version of this particular vehicle. Manufacturers generally introduced a small number of updates to their vehicles every year, and the term 'model year' indicates which version of it is independent from the date of registration. As an example, it would be possible to purchase a new car today that would wear a 2024 registration but because of when it was manufactured it could be a 2023 model year and so not benefit from the latest updates.