Car Number.

Hello, I am from the non-English Speaking Country.

With this chance, I would like to ask you a question about the car number.

I mean, usually, how do you use the words - car number?

or do the words refer to the numbers written on the board at the back & front of the car?

thanks!

The only time "car number" would be a normal term is when there's some special numbering of cars. For instance, in a race, cars will be assigned numbers so that people can keep track of them. Or, police departments will number their cars. Otherwise, we use the term "license plate number" (or some subset of that phrase) for the number on the front and back. There's also a VIN, or Vehicle Identification Number, that's written on various parts of the car and is used for such purposes as identifying stolen cars. We also don't refer to it as a "board", but a " license plate". Finally, keep in mind that the word "the" is used when something has been identified. If there were only one non-English speaking country, or if you had told us what country country you were from, then "the non-English speaking country" would appropriate. Since neither is the case, it should be "a non-English speaking country".

The board with numbers on the front and back of the car can be referred to (in British English) as the "(car) number plate".

The sequence of letters and numbers themselves are referred to as a Car Registration Number.

This is the number read by speedcameras, and written down by traffic wardens when they issue you with a parking ticket.

I should have clarified that I was speaking of American English. The other two posters appear to be British. And I find "issue you with a parking ticket" odd, since "parking ticket" is the direct object and thus should not take a preposition.

<when they issue you with a parking ticket>

This is idiomatic in BrE. Compare "supply you with", "provide you with":

a. "But since I haven''t the ability to provide you with what you want, I recognize that I''ve no right to stand in your way."

b. "I shall leave it here for you by the bedroom candles, and will be happy to supply you with more should you require it. With these words the United States Minister laid the bottle down on a marble table, and, closing his door, retired to rest."

(Wharton and Wilde respectively.)