This is the 8267th most frequent Chinese word.
is
In Chinese, there is no direct equivalent for "is"; its function is often conveyed by "是" (shì), meaning "to be."
This sentence uses '是' to indicate the identification of someone's relation to the speaker.
他是我的哥哥。
He is my older brother.
In this context, '是' is used to emphasize the correctness of the subject.
问题的答案是正确的。
The answer to the problem is correct.
Here, '是' is used to introduce and affirm the subject's characteristic description.