Llevo leídos cuatro capítulos de la novela, y esta noche quiero escribir un resumen breve.

This is a very common Spanish pattern:

llevar + past participle + amount/object

It means something like:

• to have ... done so far
• to be ... into / through something
• to have already completed this much

So llevo leídos cuatro capítulos means I’ve read four chapters so far.

The verb llevar here does not mean its basic idea of to carry. It expresses accumulated progress up to now.

Because in this structure, the past participle often agrees with the thing that has been completed.

Here, the thing read is cuatro capítulos, which is:

• masculine
• plural

So the participle becomes:

• leído = masculine singular
• leída = feminine singular
• leídos = masculine plural
• leídas = feminine plural

That is why the sentence has leídos.

Compare:

• Llevo leída una novela.
• Llevo leídos cuatro capítulos.
• Llevo hechas dos tareas.

Both can translate as I have read four chapters, but they are not exactly the same in feel.

He leído cuatro capítulos

• simply states the action has happened

Llevo leídos cuatro capítulos

• emphasizes progress up to this point
• suggests the book is still in progress
• often sounds like so far, I’m four chapters in

So in this sentence, llevo leídos fits well because the speaker seems to be in the middle of reading the novel and is reporting current progress.

Yes. That is also correct.

Both patterns are used:

• Llevo leídos cuatro capítulos
• Llevo cuatro capítulos leídos

They are very close in meaning. The version in your sentence places more immediate focus on the completed-reading idea through leídos before the quantity. The other version may feel a bit more straightforward to some learners because the number comes earlier.

You should understand both.

Because novela is a feminine noun.

So:

• de + la novela = de la novela

Spanish only contracts de + el into del:

• del libro
• del capítulo

But it does not contract with la:

• de la novela
• de la casa

So del novela would be incorrect.

Esta noche means tonight.

It is a standard way to refer to the night of the current day. In the sentence, it tells you when the speaker wants to write the summary.

So:

• esta noche quiero escribir... = tonight I want to write...

Spanish often uses a present-tense verb plus a time expression to refer to the near future, especially with verbs like querer, ir a, or simple present in context.

Because quiero escribir means I want to write, so it expresses intention or desire, not just a neutral future fact.

Compare:

• Esta noche quiero escribir un resumen breve.
  = Tonight I want to write a short summary.

• Esta noche escribiré un resumen breve.
  = Tonight I will write a short summary.

The first focuses on the speaker’s plan or wish. The second sounds more definite.

In Spanish, adjectives often come after the noun, especially when they are simply describing it in a neutral way.

So:

• un resumen breve = a brief/short summary

This is the most normal placement here.

You may also see un breve resumen, which is also correct. Putting the adjective before the noun can sometimes sound a little more literary, subjective, or stylistically marked. In everyday usage, resumen breve is very natural.

In Spanish, a comma before y is usually not required when linking two simple clauses with the same subject. So many writers would also write:

Llevo leídos cuatro capítulos de la novela y esta noche quiero escribir un resumen breve.

However, the comma can appear to:

• mark a pause
• separate two fairly long related ideas
• improve rhythm or clarity

So in this sentence, the comma is acceptable, though some style guides would prefer leaving it out.

Yes, very often. It is a useful structure for talking about progress.

Examples:

• Llevo hechas tres páginas del informe.
  = I’ve done three pages of the report so far.

• Llevo vistos dos episodios.
  = I’ve watched two episodes so far.

• Llevo aprendidas muchas palabras nuevas.
  = I’ve learned many new words so far.

• Llevo recorridos diez kilómetros.
  = I’ve covered ten kilometres so far.

It is especially common when you mention:

• a quantity
• a portion of something
• progress within an unfinished task

The sentence is perfectly natural in Spain, and the structure is understood widely in the Spanish-speaking world.

That said, llevar + participle is especially common in everyday Spanish when talking about progress, and learners often notice it a lot in Spain. In some contexts, speakers elsewhere might more often choose simpler alternatives such as:

• He leído cuatro capítulos hasta ahora.
• Ya he leído cuatro capítulos.

But llevo leídos cuatro capítulos is absolutely standard and very useful to know.

Because Spanish usually leaves out subject pronouns when the verb ending already makes the subject clear.

Here:

• llevo already means I carry / I have so far
• quiero already means I want

So yo is unnecessary unless the speaker wants emphasis or contrast:

• Yo llevo leídos cuatro capítulos, pero tú solo uno.

Without emphasis, Spanish normally prefers the version without yo.