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 wo mimasita.
I am a Japanese (language) student.
私は日本語の学生です。 watasi ha 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 ha nihonzin 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.