Mi hermana lleva las uñas cortas porque le resulta más cómodo escribir en el portátil.

Yes, llevar often means to carry or to take, but it also has another very common meaning: to wear or to have in a certain style.

So lleva las uñas cortas means:

• she wears her nails short
• she keeps her nails short

It sounds more like a habitual or chosen style than just a simple description.

Compare:

• Tiene las uñas cortas = she has short nails
• Lleva las uñas cortas = she wears/keeps her nails short

Both are possible, but llevar is very natural when talking about hair, clothes, beard, nails, etc.

Spanish often uses the definite article with body parts when it is already obvious who they belong to.

So:

• Mi hermana lleva las uñas cortas = My sister keeps her nails short

Spanish does not need sus here because mi hermana already tells us whose nails they are.

This is very common with body parts:

• Me duele la cabeza = My head hurts
• Se lavó las manos = He/She washed his/her hands

You could say sus uñas, but it would usually sound more emphatic, contrastive, or less natural in this kind of sentence.

Because cortas has to agree with uñas.

• uña is feminine
• uñas is plural

So the adjective must also be:

• feminine plural → cortas

Agreement in Spanish is very important:

• el libro rojo
• la casa roja
• los libros rojos
• las uñas cortas

It can mean either fingernails or toenails depending on context.

In this sentence, it clearly means fingernails, because the reason given is:

• escribir en el portátil = typing/writing on a laptop

That makes fingernails the only sensible interpretation here.

This is a very useful Spanish structure.

Resultar + adjective + a alguien means something like:

• to be
• to feel
• to turn out to be
• to be found

So le resulta más cómodo escribir en el portátil means:

• writing on the laptop is more comfortable for her
• she finds it more comfortable to write on the laptop

A more literal breakdown is:

• le = to her
• resulta = is / turns out / proves
• más cómodo = more comfortable

So literally: Writing on the laptop turns out more comfortable to her.

Because le is part of the verb structure with resultar.

In le resulta más cómodo, the person who experiences the comfort is expressed with an indirect object pronoun:

• me resulta cómodo = it’s comfortable for me
• te resulta cómodo = it’s comfortable for you
• le resulta cómodo = it’s comfortable for him/her

Even though mi hermana is already mentioned, Spanish still normally uses the pronoun:

• A mi hermana le resulta más cómodo...
• Mi hermana... porque le resulta más cómodo...

That le refers back to mi hermana.

Because cómodo does not describe mi hermana. It describes the action escribir en el portátil.

In Spanish, an infinitive phrase like escribir en el portátil is treated as a singular idea, and adjectives used this way normally appear in the masculine singular form.

So:

• Es cómodo escribir aquí
• Le resulta difícil estudiar
• Nos parece útil practicar cada día

Even if the person is female, the adjective stays masculine singular because it refers to the action, not the person.

Because Spanish often uses the infinitive to talk about an activity in a general way.

Here, escribir en el portátil functions like:

• writing on the laptop
• to write on the laptop

So the sentence is talking about the activity itself, not about one specific act of writing.

This is very common:

• Fumar es malo = Smoking is bad
• Viajar es caro = Travelling is expensive
• Leer me relaja = Reading relaxes me

In this sentence, escribir en el portátil is the natural way to say to write/type on the laptop.

Why en? Because Spanish often uses en with devices, screens, or surfaces where something appears or is done:

• escribir en el ordenador
• leer en la tableta
• ver algo en el móvil

Con el portátil would mean with the laptop or using the laptop, which is possible in some contexts, but here en el portátil is the more idiomatic choice for typing/writing on it.

Yes. Originally, portátil is an adjective meaning portable.

But in Spain, el portátil is very commonly used as a noun meaning:

• laptop
• literally, short for ordenador portátil

So in Spain:

• el portátil = the laptop

This is very natural European Spanish usage. In other Spanish-speaking regions, learners may also hear:

• la laptop
• la computadora portátil
• el computador portátil

Because porque is used to give a reason.

Here the sentence is explaining why she keeps her nails short:

• porque le resulta más cómodo escribir en el portátil

Basic difference:

• porque = because
• por qué = why? / for what reason?

Compare:

• ¿Por qué lleva las uñas cortas? = Why does she keep her nails short?
• Porque le resulta más cómodo escribir en el portátil. = Because it’s more comfortable for her to type on the laptop.

Yes. Spanish word order is fairly flexible, especially with phrases like this.

For example, these are also possible:

• Mi hermana lleva las uñas cortas porque escribir en el portátil le resulta más cómodo.
• Porque le resulta más cómodo escribir en el portátil, mi hermana lleva las uñas cortas.

The original version is very natural and neutral. It puts the reason after porque, and within that reason it puts le resulta más cómodo before the infinitive phrase.

Yes, there is an implied comparison, even though Spanish does not state the second part explicitly.

Más cómodo suggests:

• more comfortable than having long nails
• more comfortable than writing with long nails
• more comfortable for writing on a laptop

Spanish often leaves that comparison understood from context.

So the sentence does not need to say:

• más cómodo que llevarlas largas

It is already clear from the situation.

Yes, very much so.

The use of lleva las uñas cortas usually suggests a regular choice or ongoing style:

• she normally keeps her nails short

And the present tense in:

• le resulta más cómodo

also sounds like a general truth for her, not just something happening once today.

So the whole sentence naturally suggests:

• this is her usual preference because typing is more comfortable that way.