Ni iros al la biblioteko, kaj poste ni trinkos teon en la kafejo.

In Esperanto, -os marks the future tense.

• iri = to go

• iros = will go

• trinki = to drink
• trinkos = will drink

So:

• Ni iros = We will go
• ni trinkos = we will drink

This ending is the same for all persons, so Esperanto does not change the verb the way English does with I go / he goes.

Because the two prepositions mean different things:

• al = to, toward
• en = in, inside, at

So:

• al la biblioteko = to the library
  This shows movement toward a place.

• en la kafejo = in the café
  This shows where the tea-drinking happens.

A helpful way to think about it:

• al answers Where to?
• en answers Where?

The -n shows the direct object.

In this sentence, teon is the thing being drunk, so it takes the accusative ending:

• teo = tea
• teon = tea, as the direct object

Compare:

• Ni trinkos teon. = We will drink tea.
• Ni vidas la kafejon. = We see the café.

In both cases, the thing directly affected by the verb gets -n.

Because they are already introduced by prepositions:

• al la biblioteko
• en la kafejo

In Esperanto, a noun after a preposition usually does not need -n, because the preposition already shows its role.

So:

• al la biblioteko = to the library
• en la kafejo = in the café

The -n is mainly used for direct objects, and sometimes for motion in certain expressions, but not here.

La is the Esperanto definite article, meaning the.

So:

• la biblioteko = the library
• la kafejo = the café

Esperanto has only one definite article: la. It does not change for gender, number, or case in form.

Also, Esperanto has no indefinite article, so:

• biblioteko can mean a library or just library depending on context
• la biblioteko means the library

Because teon here means tea in a general, non-specific sense.

In Esperanto, as in English, you often do not use the definite article with a mass noun when you mean it generally:

• trinki teon = to drink tea

If you said la teon, it would usually mean a specific tea already known from context, such as:

• Ni trinkos la teon, kiun vi mendis.
  = We will drink the tea that you ordered.

So in your sentence, no article is the natural choice.

Yes, often it can.

You could say:

• Ni iros al la biblioteko, kaj poste trinkos teon en la kafejo.

This still means We will go to the library, and afterward drink tea in the café.

Because the subject stays the same, Esperanto often allows it to be left out in the second clause. However, repeating ni is also perfectly correct and can make the sentence clearer, especially for learners.

Poste means afterward, later, or then.

It shows that the second action happens after the first one:

1. Ni iros al la biblioteko
2. poste ni trinkos teon en la kafejo

So it marks sequence in time.

It comes from post = after, with the adverb ending -e:

• post = after
• poste = afterward / later

Not completely. Esperanto word order is fairly flexible, although the usual order is similar to English: subject + verb + complements/object.

The original sentence:

• Ni iros al la biblioteko, kaj poste ni trinkos teon en la kafejo.

is natural and standard.

You might also see variations like:

• Poste ni trinkos teon en la kafejo.
• Ni trinkos poste teon en la kafejo.

But some orders sound more natural than others. For learners, the original structure is a very good model.

Kaj means and. It joins the two parts of the sentence:

• Ni iros al la biblioteko
• poste ni trinkos teon en la kafejo

Without kaj, the connection between the two clauses would be less explicit. Using kaj makes it clear that these are two linked actions in one sentence.

So:

• kaj = and

Esperanto words are often built from clear parts:

• biblioteko = library
  This is basically a borrowed root used as one word.

• kafejo = café / coffeehouse
  Here you can clearly see:

  • kaf- = coffee
  • -ej- = place for
  • -o = noun ending

So kafejo literally means something like a place for coffee.

This is a very common Esperanto pattern:

• lernejo = school (a place for learning)
• kuirejo = kitchen (a place for cooking)

Esperanto pronunciation is regular, and the stress is almost always on the second-to-last syllable.

A rough guide:

• Ni = nee
• iros = EE-ros
• al = ahl
• la = lah
• biblioteko = bib-lee-o-TE-ko
• kaj = kai
• poste = POS-te
• trinkos = TRIN-kos
• teon = TE-o-n
• en = en
• la kafejo = lah ka-FEY-o

The stressed syllables are:

• biblioTEko
• POSte
• TRINkos
• TEon
• kaFEjo

One extra note: j in Esperanto sounds like English y, so kafejo sounds like ka-FEY-o, not ka-fey-jo with an English j sound.