Ni aŭskultas la sonlibron en la aŭto.

In Esperanto, all present-tense verbs end in -as. So aŭskultas means listen or are listening, depending on context.

Esperanto does not normally make a separate form for we listen versus we are listening. The same verb form covers both ideas.

Because aŭskulti works differently from English listen to. In Esperanto, aŭskulti is a direct transitive verb, so it can take an object directly:

Ni aŭskultas la sonlibron = We are listening to the audiobook

So Esperanto does not need an extra word corresponding to English to here.

Aŭskulti means to listen: to pay attention to sound on purpose.

Aŭdi means to hear: to perceive sound, whether you intend to or not.

So this sentence uses aŭskultas because the action is intentional: we are listening to the audiobook.

La is the Esperanto word for the. It is the only definite article in Esperanto.

So:

la sonlibron = the audiobook

Esperanto has no separate word for a or an. If you just said sonlibron without la, it would usually mean an audiobook or just audiobook in a less specific sense.

The -n marks the direct object. That means it marks the thing directly affected by the action.

Here:

• ni = the ones doing the listening
• la sonlibron = the thing being listened to

So sonlibro becomes sonlibron because it is the direct object.

It is a compound word:

• sono = sound
• libro = book

So sonlibro literally means sound-book, which is the Esperanto word for audiobook.

Compound words are very common in Esperanto.

En la aŭto means in the car. It gives the location where the action happens.

• en = in
• la aŭto = the car

So the sentence says that the listening is happening while the speakers are in the car.

For the same reason as with la sonlibron: la means the.

So:

• la aŭto = the car
• aŭto = a car or just car in a more indefinite sense

In this sentence, la aŭto suggests a specific car, just as English the car does.

Not if you want the same meaning.

• en la aŭto = in the car (location)
• per aŭto = by car (means of transport)

So this sentence is about where the listening happens, not about the method of travel.

Yes. Esperanto word order is fairly flexible, especially because the -n on sonlibron shows that it is the object.

For example, these are also possible:

En la aŭto ni aŭskultas la sonlibron.
La sonlibron ni aŭskultas en la aŭto.

The original sentence is just the most neutral and straightforward order.

Aŭ is pronounced roughly like ow in cow.

So:

• aŭto sounds roughly like OW-to
• aŭskultas begins with that same ow sound

One nice feature of Esperanto is that pronunciation is very regular, so words are usually pronounced exactly as they are written.