Leí un libro sobre la guerra.

Leí is the 1st person singular preterite form of leer (to read), so it means I read in the sense of I read / I finished reading at a specific time in the past.

• leo = I read / I am reading (present)
• leía = I was reading / I used to read (imperfect)
• leí = I read (completed past action)

So Leí un libro sobre la guerra presents the reading as a completed event.

The accent mark in leí shows that the e and í are pronounced in separate syllables: le-í.

Without the accent, Spanish spelling rules might suggest a different pronunciation. The accent helps mark the stress and the hiatus clearly.

So:

• leí = two syllables
• pronunciation: roughly leh-EE

Spanish often drops subject pronouns when the verb form already shows who is doing the action.

In leí, the ending -í already tells you the subject is I. So:

• Leí un libro sobre la guerra = I read a book about the war
• Yo leí un libro sobre la guerra is also possible, but yo is usually added only for emphasis, contrast, or clarity.

This is very normal in Spanish.

Un is the form used before a masculine singular noun.

• un libro = a book
• uno is usually used as a number (one) or as a pronoun in some contexts, not directly before a masculine singular noun in this way.

So:

• correct: un libro
• not correct here: uno libro

Here sobre means about or on the subject of.

So:

• un libro sobre la guerra = a book about the war

Sobre can also literally mean on / over / above, but in this sentence it means about.

Other possible ways to say about exist, such as acerca de, but sobre is very common and natural here.

Spanish often uses the definite article more than English does.

In sobre la guerra, la guerra means the war. This can refer to:

• a specific war already understood from context, or
• war as a general topic, where Spanish often still uses the article

English sometimes says about war, but Spanish very often prefers sobre la guerra in this kind of sentence.

This is the most neutral and natural word order:

• Leí = verb
• un libro = direct object
• sobre la guerra = phrase describing libro

You could change the order in special contexts, but it may sound marked or literary. For example:

• Un libro sobre la guerra leí sounds unusual in ordinary conversation

So for learners, the standard order here is the best one to use.

In this sentence, sobre la guerra describes libro.

So the meaning is:

• I read [a book about the war]

It does not usually mean:

• I read about the war

If you wanted to say I read about the war, a more direct option would be:

• Leí sobre la guerra

So the presence of un libro changes the structure and meaning.

Guerra is pronounced roughly GEH-rra.

A few key points:

• gue sounds like geh
• the u is silent in gue
• rr is a strong rolled or trilled r
• stress falls on gue

So:

• guerra = GEH-rra
• not goo-EH-rra

In Spanish spelling, gue and gui normally have a silent u.

So:

• guerra = geh-rra
• guitarra = gee-TA-rra

If Spanish wants the u to be pronounced in gue/gui, it uses a diaeresis:

• vergüenza
• pingüino

But in guerra, there is no diaeresis, so the u stays silent.

No, not naturally.

Leí is preterite, which presents the action as a completed event in the past. It does not usually mean I used to read.

For repeated or habitual past actions, Spanish normally uses the imperfect:

• Leía libros sobre la guerra = I used to read books about war
• Leía un libro sobre la guerra = I was reading a book about the war

So Leí un libro sobre la guerra means a completed reading event.

Yes, but the meaning changes slightly.

• Leí un libro sobre la guerra = I read a book about the war
• Leí sobre la guerra = I read about the war

In the original sentence, the speaker specifically mentions a book as the thing read. Without libro, the sentence becomes more general.

Yes. Acerca de also means about.

So these are both possible:

• Leí un libro sobre la guerra
• Leí un libro acerca de la guerra

In many contexts, sobre is shorter and very natural. Acerca de can sound a little more formal or careful, depending on context, but both are correct.