Antes de girar a la derecha, mi madre puso el intermitente y miró el retrovisor.

Because Spanish normally uses antes de + infinitive to mean before doing something.

• antes de girar = before turning
• antes de salir = before leaving
• antes de comer = before eating

Here, girar is an infinitive, just like to turn in English.

A useful comparison:

• Antes de girar, mi madre... = Before turning, my mother...

If Spanish needs to mention a different subject, it often changes to antes de que + subjunctive:

• Antes de que mi madre girara, yo le hablé.
  = Before my mother turned, I spoke to her.

Because after antes de, Spanish usually uses the infinitive when talking about an action in a general way, without separately conjugating it.

So:

• Antes de girar = Before turning

This is similar to English before turning, not before she turned.

Even though the person doing the action is mi madre, Spanish does not need to repeat or conjugate the verb here.

In a driving context, girar a la derecha means to turn right.

• girar = to turn
• a la derecha = to the right / right

So:

• girar a la derecha = turn right

In everyday Spanish, especially in some places, you may also hear doblar a la derecha, but girar a la derecha is completely standard and clear.

Because Spanish normally uses the pattern girar a la derecha / a la izquierda.

The preposition a is part of the expression:

• a la derecha = to the right
• a la izquierda = to the left

So the full phrase is:

• girar a la derecha = to turn right

This is just how Spanish expresses direction here.

Because the normal way to say my mother in Spanish is mi madre.

Spanish possessives like mi, tu, su, nuestro usually go before the noun:

• mi madre = my mother
• mi coche = my car

Forms like la madre mía are not the normal neutral way to say it here.

Puso is the preterite form of poner.

• poner = to put, to place, or in some contexts to switch on / put on
• puso = he/she put or he/she switched on

In this sentence, puso el intermitente means something like:

• she put on the turn signal
• more naturally in English: she signaled or she turned on the indicator

It is irregular, so it does not follow the normal pattern of regular -er or -ir verbs.

Yes, literally it is something like put the indicator, but this is a normal Spanish expression.

In Spain, poner el intermitente means:

• to turn on the indicator
• to use the turn signal

So although the literal wording may feel unusual to an English speaker, it is a very natural driving expression in Spanish.

Here, el intermitente means the turn signal / indicator.

In Spain, this is a very common word in driving contexts.

Depending on the country, other expressions may exist, but for Spain:

• poner el intermitente = to signal / to turn on the indicator

So this sentence sounds very natural for Peninsular Spanish.

Retrovisor means rear-view mirror or simply mirror in a driving context.

So:

• miró el retrovisor = she looked at the rear-view mirror

In context, Spanish often uses the singular if one mirror is being referred to generally or if the specific mirror is understood from the situation.

Spanish often uses the definite article more than English does.

So where English might sometimes say:

• turned on her indicator
• looked in the rear-view mirror

Spanish naturally says:

• puso el intermitente
• miró el retrovisor

This does not necessarily mean the in a very emphatic sense. It is often just the normal way Spanish refers to familiar, specific objects in context.

Because the sentence describes completed actions in a sequence.

• puso = she turned on / she put on
• miró = she looked

The preterite is commonly used for finished events:

1. she signaled
2. she looked in the mirror

These are seen as specific, completed actions before the turn.

If the sentence were describing background or ongoing action, Spanish might use the imperfect instead, but here the preterite is the natural choice.

Because miró is the third-person singular preterite of mirar:

• yo miré
• tú miraste
• él/ella miró

The accent helps distinguish pronunciation and, in writing, separates it from other forms.

For example:

• miro = I look
• miró = he/she looked

So the accent is important.

Because Spanish often omits subject pronouns and does not need to repeat the subject if it is already clear.

In this sentence:

• mi madre puso el intermitente y miró el retrovisor

After mi madre, it is clear that both verbs refer to her:

• she turned on the indicator
• and looked in the mirror

Spanish prefers this kind of economy when the subject is obvious.

Yes. A natural English translation would often be something like:

• Before turning right, my mother signaled and checked the rear-view mirror.
• Before turning right, my mother put on the indicator and looked in the rear-view mirror.

A very literal translation is useful for learning, but a more natural English version may sound smoother.

It is normal and helpful here because the sentence begins with a longer introductory phrase:

• Antes de girar a la derecha, ...

In Spanish, a comma is commonly used after this kind of opening time expression, especially when it is a bit long.

So the comma is natural and good style.