Es mejor que la conductora mire el retrovisor antes de girar a la izquierda.

Because es mejor que normally triggers the subjunctive in Spanish.

• mire = present subjunctive of mirar
• mira = present indicative

Spanish uses the subjunctive here because the sentence expresses a recommendation or what is preferable, not a simple statement of fact.

So:

• Es mejor que la conductora mire... = correct
• Es mejor que la conductora mira... = not correct

Que introduces a new clause: that the driver look...

In Spanish, when you say It is better that..., you usually need:

• es mejor que + subjunctive

So the structure is:

• Es mejor que + [subject] + [subjunctive verb]

If you do not want a full clause, Spanish often uses an infinitive instead:

• Es mejor mirar el retrovisor antes de girar a la izquierda.

That version means It is better to look in the mirror before turning left.

Yes — in many situations that is very natural.

There is an important difference:

• Es mejor que la conductora mire...
  = focuses on the driver as the person who should do it
• Es mejor mirar...
  = more general, more like It is better to look...

Spanish often prefers the infinitive when the idea is general or when no separate subject needs to be emphasized.

Because conductora is the feminine form of conductor, meaning driver.

• el conductor = the male driver / driver (masculine form)
• la conductora = the female driver

The sentence is specifically referring to a female driver, so la conductora is used.

In Spain, conductor/conductora is the normal word for driver. A word like chofer exists, but it is less neutral and less standard in this kind of sentence.

Spanish often uses the definite article where English would use a possessive like her, his, or your, especially when the object is obvious from the context.

So in a driving context:

• mirar el retrovisor = look at the mirror

This sounds natural because everyone understands it is the relevant mirror in the car.

You can say su retrovisor, but it sounds more explicit, and sometimes more contrastive, like you are stressing whose mirror it is.

By itself, retrovisor can be a general word for a car mirror used to see behind you. Context decides exactly which one.

If you need to be specific, Spanish can say things like:

• retrovisor interior = interior rear-view mirror
• retrovisor exterior = exterior mirror / side mirror

In everyday usage, el retrovisor often works if the exact mirror is clear from context.

After antes de, Spanish normally uses an infinitive when no new subject is introduced.

So:

• antes de girar = before turning

This is the standard pattern.

If Spanish introduces a different subject, then you often get:

• antes de que + subjunctive

For example:

• Es mejor que la conductora mire el retrovisor antes de que el coche gire.

But in your sentence, the turning is done by the same person already being discussed, so antes de girar is the natural choice.

It is understood to be the driver.

In Spanish, an infinitive like girar does not show the subject directly, so the subject is usually understood from the previous clause or from context.

Here, the natural reading is:

• la conductora mire el retrovisor antes de girar
• the driver should check the mirror before she turns

So the subject of girar is implicit.

Because Spanish normally uses the article in these fixed direction expressions:

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

This is simply the normal idiomatic form. You do not usually say just a izquierda.

With verbs of turning, the full expression is:

• girar a la izquierda
• girar a la derecha

In Spain, girar a la izquierda sounds very natural and standard.

In some parts of Latin America, doblar a la izquierda is also very common. Spanish speakers will understand both, but for Spain Spanish, girar is a very safe and natural choice.

So for a learner focused on Spain:

• girar a la izquierda = excellent choice

Mire is the present subjunctive, third person singular, of mirar.

The pattern is:

• infinitive: mirar
• yo form: miro
• stem for present subjunctive: mir-
• subjunctive ending: -e
• result: mire

Here it matches la conductora, which is third person singular.

Sometimes yes, but here la conductora is helpful because it clearly tells you who should act.

Spanish often leaves out subject pronouns, but noun subjects can also be omitted when the context is obvious. For example, if everyone already knows you are talking about the driver, you might hear:

• Es mejor que mire el retrovisor antes de girar a la izquierda.

However, without context, that could sound less clear, because mire could also be interpreted as a formal usted form. So keeping la conductora makes the sentence precise.