The term "plaque d'immatriculation" in French means "license plate" or "number plate," which is an official sign on the front and back of a vehicle showing its registration number.

The code "UA" on a license plate stands for Ukraine. It is the ISO 3166-2 country code used internationally to identify vehicles registered in Ukraine. Ukrainian plates feature this "UA" code along with the colors of the Ukrainian flag (blue and yellow) on the left side of the plate.

License plates generally include a country code to indicate the country where the vehicle is registered. For European Union countries, this is typically displayed on the blue strip called an "euroband" on the left side of the plate. The country code consists of one to three letters representing the country in either English or the national language. For example, "F" represents France, and "UA" represents Ukraine.

Summary:

• "Plaque d'immatriculation" means "license plate" or "number plate" in English.
• "UA" is the country code for Ukraine on vehicle registration plates.
• The country code identifies the nation of vehicle registration, often displayed on the left blue band of the plate in Europe.

If further details are desired, such as specific format or appearance of Ukrainian plates, additional explanations can be provided.