You've already learned that the particle の can be used to express possession and that we can place it next to a pronoun to make the words my, yours, his, and hers.
This is not the only use of the particle の however. It can be used in many situations where we don't use a possessive construction in English. The function of の is often to describe the noun that follows it in terms of the noun that precedes it.
|I saw a Japanese car.||日本 の 車 を 見ました。nihon no kuruma o mimashita.|
|I am a Japanese (language) student.||私 は 日本語 の 学生 です。watashi wa nihongo no gakusei desu.|
|You are a Japanese studenthaving the Japanese nationality.||あなた は 日本人 の 学生 です。anata wa nihonjin no gakusei desu.|
As you can see in the sentences above, when we put の after a noun, it basically makes the noun behave as an adjective.
Until now, we have used counters after the words they count. A counter can however also be used in front of the word it counts if we put の after the counter.