This is the 289th most frequent Chinese word.
山
Mountain.
In this sentence, the word '山' (mountain) is used as a noun to refer to a physical geographic feature.
这座山非常高。
This mountain is very tall.
Here, '山' is used metaphorically to describe steadfastness or strength.
我们的友谊像大山一样坚定。
Our friendship is as strong as a mountain.
In this example, '山' is part of the verb phrase '爬山' (to climb mountains), referring to the activity of mountain climbing.