Por si acaso, llevo desmaquillante, una horquilla y una rebeca en la mochila cuando duermo fuera de casa.

Por si acaso means just in case.

It is a very common fixed expression in Spanish and is used when you do something as a precaution. In this sentence, it gives the idea that the speaker takes these items in case they might need them.

A few similar English translations are:

• just in case
• as a precaution
• in case

You do not need to translate it word for word. Although it literally looks like for if by chance, learners should treat por si acaso as a set phrase.

Llevo is from llevar, which often means to carry, to take, or to bring along.

Here, llevo means something like:

• I take
• I carry
• I bring along

So llevo desmaquillante, una horquilla y una rebeca... means the speaker packs or takes those items with them.

Why not traigo?

• Traer usually focuses on bringing something toward the place where the speaker/listener is.
• Llevar usually focuses on taking something with you.

Why not me llevo?

• Me llevo is also possible in some contexts, especially when emphasizing that I take something with me.
• But llevo is perfectly natural here and sounds simple and neutral.

Spanish often uses the present tense for habitual actions or things someone generally does.

So this sentence means:

• When I sleep away from home, I take makeup remover, a hairpin, and a cardigan in my backpack.

It describes a routine or usual habit, not a one-time future action.

That is why:

• llevo = I take / I usually take
• duermo = I sleep / when I sleep

Using the future would change the meaning and suggest a specific later event rather than a general habit.

Spanish usually omits subject pronouns when they are clear from the verb ending.

• llevo already tells you the subject is I
• duermo also tells you the subject is I

So yo is unnecessary unless the speaker wants to add contrast, emphasis, or clarity.

For example:

• Yo llevo desmaquillante, pero ella no.
  = I take makeup remover, but she doesn’t.

In your sentence, there is no need for yo.

Here, desmaquillante is being used as a noun.

It means makeup remover.

This word comes from the idea of removing makeup:

• maquillaje = makeup
• desmaquillar = to remove makeup
• desmaquillante = makeup-removing product / makeup remover

In real life, Spanish often uses product names like this without adding another noun such as producto or líquido.

So:

• llevo desmaquillante = I take makeup remover

This is completely natural.

This is a very natural difference in Spanish.

Desmaquillante is being treated more like an uncountable substance/product, similar to:

• llevo agua
• llevo champú
• llevo crema

So no article is needed.

But una horquilla and una rebeca are countable singular objects, so Spanish uses the indefinite article:

• una horquilla = a hairpin
• una rebeca = a cardigan

So the pattern is:

• desmaquillante → product/substance idea
• una horquilla, una rebeca → individual items

Horquilla usually means a hairpin or bobby pin.

Depending on context, English speakers might loosely think of it as a hair accessory used to hold hair in place, but the most direct translation is usually:

• hairpin
• sometimes bobby pin

It is not always the same as a larger hair clip. A clip would more often be something like pinza para el pelo.

So una horquilla is typically a small pin used in the hair.

Yes, rebeca is a very common word in Spain Spanish for a cardigan.

So:

• una rebeca = a cardigan

This is useful for learners because it may be less common or unfamiliar in some varieties of Spanish outside Spain. In other places, people might say things like:

• cárdigan
• suéter
• chaqueta, depending on the region and the exact garment

But in Spain, rebeca is a very normal everyday word.

Because en la mochila means in the backpack.

The preposition en is used for location: something is inside or in something.

• en la mochila = in the backpack

If you used a, that would suggest movement to a place, which is not what the sentence is focusing on.

The sentence is describing where the items are carried:

• llevo ... en la mochila = I carry ... in my backpack

Cuando duermo fuera de casa means:

• when I sleep away from home
• when I stay somewhere other than home overnight

Breakdown:

• cuando = when
• duermo = I sleep
• fuera de casa = outside the home / away from home

In natural English, sleep outside the house could sound like sleeping outdoors, but that is not the meaning here.

Dormir fuera de casa is a normal expression for sleeping somewhere else, such as:

• at a friend’s house
• in a hotel
• at a partner’s place
• while travelling

Because casa often appears without an article when it means home in a general, personal sense.

So:

• estar en casa = to be at home
• ir a casa = to go home
• salir de casa = to leave home
• fuera de casa = away from home

If you say la casa, it sounds more like the house/building as a physical object, not the idea of home.

So in this sentence:

• fuera de casa = away from home

That is the idiomatic choice.

Dormir is a stem-changing verb.

Its infinitive is:

• dormir = to sleep

In the present tense, the o changes to ue in most forms:

• duermo = I sleep
• duermes = you sleep
• duerme = he/she sleeps
• dormimos = we sleep
• dormís = you all sleep (Spain)
• duermen = they sleep

So duermo is the correct yo form.

This is a very common kind of Spanish verb change.

Yes, absolutely.

Both of these are natural:

• Por si acaso, llevo desmaquillante, una horquilla y una rebeca en la mochila cuando duermo fuera de casa.
• Cuando duermo fuera de casa, llevo desmaquillante, una horquilla y una rebeca en la mochila, por si acaso.

Spanish word order is often more flexible than English, especially with time expressions and short phrases like por si acaso.

However, moving parts around can slightly change the focus:

• starting with Por si acaso emphasizes the precaution
• starting with Cuando duermo fuera de casa emphasizes the situation

Both are grammatically fine.

It applies to the whole idea of taking those items.

So the meaning is that the speaker takes:

• makeup remover
• a hairpin
• and a cardigan

just in case they might need them.

It does not only refer to una rebeca. The phrase sets the overall reason for packing those things.

Yes, it is completely normal.

Spanish usually does not use a comma before y in a simple list, so this is standard:

• desmaquillante, una horquilla y una rebeca

This is similar to British English style and unlike the optional Oxford comma in English.

So the punctuation here is exactly what you would expect in standard Spanish.

Yes, a little.

The main Spain-specific feature is rebeca, which is very characteristic of Spain Spanish for cardigan.

The rest of the sentence is generally widely understandable across the Spanish-speaking world, but vocabulary choices may vary by country. For example:

• rebeca may be replaced elsewhere by cárdigan or another regional word
• horquilla may also vary somewhat depending on region and the exact object

So the sentence is perfectly normal Spanish, with a touch of Spain-specific everyday vocabulary.