La directora no dijo nada, pero su gesto y su mirada serios nos hicieron callarnos enseguida.

Because the person is female. In standard modern Spanish, many job titles change form depending on gender:

• el director = a male director/head teacher/principal
• la directora = a female director/head teacher/principal

So la directora is the natural form here.

Dijo is the preterite, which is used for a completed action in the past.

• no dijo nada = she didn’t say anything / she said nothing

If you used decía, it would sound more like background description or an ongoing/repeated action in the past:

• no decía nada = she wasn’t saying anything / she used to say nothing

Here, the sentence is talking about one specific moment, so dijo fits better.

Spanish normally uses negative concord. That means once you have no, you also use negative words like:

• nada = nothing / anything
• nadie = nobody / anybody
• nunca = never / ever

So:

• No dijo nada = She didn’t say anything

Using algo after no would not sound right here.

Because su agrees with the owner, not with the number of things owned.

Here, both the gesture and the look belong to her, so Spanish uses su:

• su gesto = her gesture
• su mirada = her look/gaze

Even with two nouns, the possessor is still one person, so su is correct.

Yes, Spanish can sometimes say su gesto y mirada, but repeating su is very common and often sounds clearer and more natural.

• su gesto y su mirada clearly treats them as two separate features
• su gesto y mirada is shorter, but a bit more compressed

So the repeated su is normal and idiomatic.

Because serios describes two nouns together:

• gesto is masculine singular
• mirada is feminine singular

When one adjective refers to a mixed group of nouns, Spanish normally uses the masculine plural:

• su gesto y su mirada serios

That is why it is serios, not serias.

It describes both.

So the meaning is:

• her serious gesture and serious look

If Spanish wanted to make the agreement explicit for each noun, it could say:

• su gesto serio y su mirada seria

But with one shared adjective after both nouns, serios naturally applies to both.

Because the subject is made of two things:

• su gesto
• su mirada serios

Together they form a compound subject, so the verb goes in the plural:

• su gesto y su mirada serios nos hicieron...
• literally: her serious gesture and look made us...

Even though each noun is singular by itself, together they trigger a plural verb.

They do two different jobs.

1) nos hicieron

This means made us.

Here, nos = us is the object of hicieron.

2) callarnos

This comes from callarse = to be quiet / to fall silent.

Here, -nos is the reflexive pronoun belonging to callarse.

So the structure is:

• hacer + someone + infinitive
• nos hicieron callarnos
• literally: they made us quiet ourselves
• natural English: they made us fall silent / made us be quiet

So the two nos are not a mistake; they belong to different parts of the sentence.

Yes, you may also hear nos hicieron callar.

There is a small nuance:

• callar can mean to silence or to stop talking
• callarse often means to become/stay quiet oneself

So:

• nos hicieron callar = they made us stop talking / they silenced us
• nos hicieron callarnos = they made us fall silent / be quiet

In practice, both are understandable, but callarnos gives a slightly more reflexive sense: we ourselves went quiet.

Enseguida means:

• right away
• immediately
• at once

So:

• nos hicieron callarnos enseguida = they made us fall silent immediately

It is a very common everyday word in Spanish.

Yes, its position is flexible.

You could also say:

• Enseguida nos hicieron callarnos
• Nos hicieron enseguida callarnos (less natural)
• Nos hicieron callarnos enseguida

The final position is very natural because it neatly adds the idea of how quickly the action happened.

They are related, but not the same.

• gesto = gesture, expression, especially facial expression
• mirada = look, gaze, the way someone looks at you

So the sentence suggests that the director didn’t need words; her expression and the look in her eyes were enough to make everyone be quiet.

A useful breakdown is:

• La directora = the headmistress/director
• no dijo nada = didn’t say anything
• pero = but
• su gesto y su mirada serios = her serious gesture and look
• nos hicieron = made us
• callarnos = be quiet / fall silent
• enseguida = immediately

So grammatically, the core structure is:

• X no hizo A, pero Y hizo B
• She didn’t do A, but her expression and gaze did B

This is a very natural Spanish way to show that someone communicated something without speaking.