There are several errors in the sentence "Ana is not intelligent." First, the word "is" should not be used to deny a quality or characteristic of a person. Instead, the word "no" should be used before the quality or characteristic in question. For example: "Ana is not intelligent" should be said "Ana is not intelligent".
In addition, the phrase can be considered offensive or discriminatory, since it is affirming that Ana has no intelligence, which is not true. Each person has a different level of intelligence and you cannot generalizeabout a person's intelligence without knowing it in depth. Therefore, it would be better not to make judgments about the intelligence of Ana or anyone else.
In summary, the sentence "Ana is not intelligent" is incorrect both in its grammatical construction and in its content.