Poor Mili! She's caught between scheming Ivo and his grandmother, who have cooked up a plan to turn her from un desastre into a more refined woman. When Mili protests to the grandmother, she takes Ivo's side:
 

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Mi nieto tiene razón. Vos sos una muchacha en estado... digamos... casi salvaje.

My grandson is right. You're a girl in a state that is... let's say... almost savage.

Captions 76-77, Muñeca Brava - 18 - La Apuesta - Part 6

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Por primera vez, la mariposa tiene razón.

For the first time, the butterfly is right.

Caption 12, Muñeca Brava - 9 - Engaños - Part 5

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While tiene razón literally means "has reason," it is best translated as "is right."

Here's another example of tener + razón

Juan tenía razón, necesitábamos mejores atacantes.
Juan was right, we needed better forwards [soccer].

Sometimes you will see tener + la razón. The meaning is the same: "to be right."

En lo que respecta a mi casa, mi esposa cree que siempre tiene la razón.
As far as my house goes, my wife believes that she is always right.

But what if you literally want to say "he has reason," as in this example?

He has reason to believe Annie will get an A.
(perhaps she is smart, she got an A last semester, the teacher likes her, etc.)

In this case we want to employ either the phrase "tener razones para" or "tener motivos para":

Él tiene razones para creer que Annie va a sacar un A.
He has reason to believe that Annie is going to get an A.

Él tiene motivos para creer Annie va a sacar un A.
He has reason to believe that Annie is going to get an A.

Also, as we touched upon in a previous lesson, "tener por qué" also means "to have reason," but you will find it used mostly in the negative sense:

Él no tiene por qué creer que Annie va a sacar un A.
He has no reason to believe that Annie is going to get an A.

No tengo por qué quejarme.

I have no reason to complain.

No tengo por qué contarte mis secretos.

I have no reason to tell you my secrets.

No tienes por qué preocuparte.

You have no reason to worry.

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On rare occasions, you will come across "tener por qué" used in the positive sense:

Ellos tienen por qué luchar.
They have reason to struggle.