The seal is called FUIN, made of aluminum with a mark on it.
It must be placed on the number plate in back and left side of the plate.
The seal is an evidence of the vehicle is registered in appropriately at motor vehicle office and passed test. It can be removed in motor vehicle office only.
What the seal mean?
It is an evidence of the registration and also for the protection against the theft.
It is violation driving a car without the seal on the number plate.