将以下句子中的错误用正确的语法纠正，并解释为什么它是错的。

He don’t have no car because he can’t afford it.
Corrected sentence: He doesn't have a car because he can't afford it.

Explanation: 

1. "He don't have no car" is incorrect because it uses a double negative, which means the two negative words “don’t” and “no” cancel each other out to create a positive statement. 

2. "Don't" should be changed to "doesn't" because the subject "he" is singular, requiring a singular verb.

3. "No" should be changed to "a" because it is incorrect to use a double negative in English.