Corrections

Correct: They are from Mexico.
Correct: They are Mexican.

Error: I don't not have a dog.
Correction: I don't have a dog.
Correction: I do not have a dog.

Error: They are my friend.
Correction: They are my friends.

Error: She is women.
Correction: She is a woman.
Correction: They are women.

Error: IT IS NOT HAPPY DOG.
Correction: it is not a happy dog.

Correct: They are not happy because they have to study.
Correct: They are happy because they have to study.

Error: She is not a tired.
Correction: She is not a tired woman.
Correction: She is not tired.
Correction: She isn't tired.

Error: I'm not Brazil.
Correction: I'm not from Brazil.

Error: It is not child smart.
Correction: It is not a smart child.
Correction: He is not a smart child.
Correction: She is not a smart child.

Error: She is my friend because is very nice.
Correction: She is my friend because she is very nice.
Correction: She is my friend and she is very nice.

Correct: He is not a teacher from Italy.
Possible meanings:
Correct: He is not a teacher, and he is not from Italy.
Correct: He is a teacher, and he is not from Italy.
Correct: He is not a teacher, and he is from Italy.

Error: You are not student.
Correction: You are not a student. (singular)
Correction: You are not students. (plural)

Error: We are not children sad.
Correction: We are not sad children.

Error: He is not a women.
Correction: He is not a woman.

Error: the boy plays with dog.
Correction: The boy plays with the dog.
Correction: The boy plays with his dog.

Error: You are a women.
Correction: You are a woman. (singular)
Correction: You are women. (plural)

Error: It is not dogs.
Correction: It is not a dog. (singular)
Correction: They are not dogs. (plural)

Error: You are a women angry.
Correction: You are an angry woman. (singular)
Correction: You are angry women. (plural)

Error: He is a hungry.
Correction: He is hungry.

Error: They are very good student children.
Correction: The students are very good children.
Correction: The children are very good students.

Error: I am not woman. I am a man.
Correction: I am not a woman. I am a man.

Error: It is of Africa.
Correction: It is from Africa.
Correction: The book is from Africa.
Correction: It is a story of Africa.
Correction: It is a story about Africa.

Correct: Is he your lover?
Correct: Is he your husband?

Error: Is my lover.
Correction: She is my lover.
Correction: She is my wife.
Correction: Is she my lover?
Correction: Is she my wife?

Error: We are happy of my dog.
Correction: We are happy with my dog.

Error: You are lover of my brother.
Correction: You are the lover of my brother.
Correction: You are my brother's lover.

Error: We are from Cuba. He is of Colombia.
Correction: We are from Cuba. He is from Colombia.

Error: You is happy of my sister.
Correction: You are happy with my sister.
Correction: You are happy for my sister.

Error: They of Columbia are happy for party.
Correction: The Columbians are happy to have a party.