En cuanto anochece, mi madre enciende la luz del pasillo.

Here en cuanto means as soon as.

So En cuanto anochece... means As soon as it gets dark...

A useful comparison:

• cuando = when
• en cuanto = as soon as

So en cuanto is a bit more immediate than cuando.

Anochece comes from the verb anochecer, which means to get dark or to fall night.

In this sentence, anochece means:

• it gets dark
• night falls

It is being used in an impersonal way, so Spanish does not need a subject like it. English says it gets dark, but Spanish simply says anochece.

It is in the present tense because the sentence describes a habitual action, something that usually happens.

So the idea is:

• Whenever / as soon as it gets dark, my mother turns on the hallway light.

Spanish often uses the present indicative for routines and general truths.

If you were talking about a future situation, Spanish would often change this structure:

• En cuanto anochezca, mi madre encenderá la luz del pasillo.
• As soon as it gets dark, my mother will turn on the hallway light.

Notice the change from anochece to anochezca.

Because Spanish often leaves out dummy subjects like English it in weather and time expressions.

English needs:

• It is raining
• It is getting dark

Spanish does not:

• Llueve
• Anochece

So in anochece, the idea of it is understood but not expressed.

Spanish usually uses a possessive like mi, tu, su, etc. when talking about family members in a neutral sentence like this.

So:

• mi madre = my mother
• mi padre = my father

You could sometimes hear family words without the possessive in certain contexts, but mi madre is the normal choice here.

Also, there is no article before mi madre:

• correct: mi madre
• not: la mi madre

That pattern is standard with possessives in modern Spanish.

Yes. Enciende comes from encender (to turn on / to light) and it is a stem-changing verb.

The change is:

• e → ie

So:

• yo enciendo
• tú enciendes
• él/ella enciende
• nosotros encendemos
• vosotros encendéis
• ellos encienden

In this sentence, mi madre is she, so we use enciende.

Because in Spanish the normal verb is encender, which means to turn on or to switch on for lights, devices, fire, etc.

So:

• encender la luz = turn on the light
• apagar la luz = turn off the light

This is just the natural collocation in Spanish.

In Spain, encender is the standard and safest verb to use for lights.

Spanish often uses the definite article where English may or may not use one.

So:

• la luz = the light
• del pasillo = of the hallway / hallway

Together:

• la luz del pasillo = the hallway light

Spanish normally includes the article here because you are referring to a specific light: the one in the hallway.

Del is the contraction of:

• de + el = del

So:

• la luz del pasillo literally means
• the light of the hallway

In natural English, we usually say:

• the hallway light

But Spanish commonly uses this noun + de + noun structure.

More examples:

• la puerta del coche = the car door
• el color del cielo = the color of the sky

Yes, you could. En cuanto se hace de noche also means as soon as it gets dark.

Comparison:

• En cuanto anochece = a bit more compact and elegant
• En cuanto se hace de noche = very common and easy to understand

Both are correct. The version with anochece is slightly more concise and feels a little more literary or polished, but it is still perfectly normal.

Yes, but the meaning changes slightly.

• Cuando anochece, mi madre enciende la luz del pasillo. = When it gets dark, my mother turns on the hallway light.

• En cuanto anochece, mi madre enciende la luz del pasillo. = As soon as it gets dark, my mother turns on the hallway light.

So en cuanto emphasizes that she does it immediately.

The comma separates the introductory time clause from the main clause:

• En cuanto anochece, → subordinate clause
• mi madre enciende la luz del pasillo. → main clause

This comma is very natural in writing and helps readability.

In short sentences, punctuation can sometimes vary a little, but using the comma here is completely standard.

Then Spanish would normally use the present subjunctive after en cuanto.

So you would say:

• En cuanto anochezca, mi madre encenderá la luz del pasillo.

Why?

Because with en cuanto, cuando, tan pronto como, etc., Spanish uses:

• indicative for habitual or known actions
• subjunctive for future actions not yet completed

So:

• En cuanto anochece... = habitual
• En cuanto anochezca... = future

Yes, in this sentence pasillo means hallway, corridor, or sometimes hall depending on the house and the context.

For most learners, hallway light is the best natural translation here:

• la luz del pasillo = the hallway light

In British English, some people might also say the hall light if they mean the light in the entrance hall or passage.