Poste mi iras al la haltejo, sed la trafiko estas tiel granda, ke la aŭtobuso malfruas.

Poste means afterwards, then, or later.

In this sentence, it comes first to show the next step in a sequence: Poste mi iras... = Then I go...

Esperanto word order is fairly flexible, so you could also see:

• Mi poste iras al la haltejo.

But putting poste first is very natural when telling a story or describing actions in order.

Iras is the present tense, from iri = to go.

Esperanto often uses the present tense when describing a sequence of events, especially in narration, routines, or step-by-step descriptions. So Poste mi iras al la haltejo can mean something like Then I go to the bus stop in a narrative sense.

If you wanted to emphasize that this happens in the future, you could say:

• Poste mi iros al la haltejo. = Then I will go to the bus stop.

So iras here is not wrong at all; it is just a natural narrative present.

Al means to or toward. It marks direction.

So:

• iri al la haltejo = to go to the bus stop

This is one of the most basic ways Esperanto shows movement toward a place.

Compare:

• Mi estas ĉe la haltejo. = I am at the bus stop.
• Mi iras al la haltejo. = I am going to the bus stop.

So al is important because it shows destination, not location.

Haltejo means stop or stopping place, and in this sentence it means bus stop.

It is built very regularly:

• halti = to stop
• -ej- = a suffix meaning place
• -o = noun ending

So:

• haltejo = a place for stopping

This is a very typical Esperanto word-building pattern. Similar examples:

• lerni = to learn → lernejo = school
• kuiri = to cook → kuirejo = kitchen

La is the definite article, meaning the.

So:

• la haltejo = the bus stop
• la aŭtobuso = the bus

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

In this sentence, la is used because the speaker means a specific stop and a specific bus in the situation being described.

Yes. In Esperanto, granda can be used for things like amount, scale, intensity, or extent, not just physical size.

So la trafiko estas tiel granda means something like:

• the traffic is so heavy
• there is so much traffic

A more word-for-word feeling is the traffic is so great.

English usually prefers heavy traffic, while Esperanto commonly uses granda in this kind of idea.

Because tiel ... ke ... is a connected pattern meaning so ... that ...

So:

• tiel granda, ke la aŭtobuso malfruas = so great/heavy that the bus is late

This structure shows cause and result.

Compare:

• tre granda = very big/great
• tiel granda, ke... = so big/great that...

You use tre when you are only describing degree. You use tiel ... ke ... when the degree leads to a consequence.

It is a very common Esperanto pattern:

• tiel = so
• adjective or adverb
• ke = that

So the full pattern is:

• tiel X, ke Y = so X that Y

In your sentence:

• la trafiko estas tiel granda, ke la aŭtobuso malfruas
• the traffic is so heavy that the bus is late

More examples:

• Li estas tiel laca, ke li tuj endormiĝas.
  • He is so tired that he falls asleep immediately.
• Ŝi kuris tiel rapide, ke mi ne povis sekvi ŝin.
  • She ran so fast that I could not follow her.

Here ke means that and introduces a subordinate clause.

So:

• ke la aŭtobuso malfruas = that the bus is late

It links the result to what came before:

• the traffic is so heavy, that the bus is late

In Esperanto, ke is very common for joining clauses:

• Mi pensas, ke li venos. = I think that he will come.
• Estas klare, ke ŝi pravas. = It is clear that she is right.

Because malfrui is a verb meaning to be late.

So:

• la aŭtobuso malfruas = the bus is late

This is very natural in Esperanto. Instead of saying something like is in a state of lateness, Esperanto often just uses a simple verb.

Related forms:

• frua = early
• malfrua = late
• malfrui = to be late
• malfruo = lateness, delay

So the sentence uses the verb form directly.

Mal- is a very common Esperanto prefix that gives the opposite meaning.

Here:

• frua = early
• malfrua = late

Then:

• malfrui = to be late

This is one of the most useful features of Esperanto. Instead of learning a completely unrelated opposite word, you can often build it with mal-.

Examples:

• bona = good → malbona = bad
• granda = big → malgranda = small
• fermi = to close → malfermi = to open

Trafiko is a collective noun, similar to English traffic. It refers to the general flow of vehicles rather than individual cars.

So Esperanto treats it as singular:

• la trafiko estas granda = the traffic is heavy

If you wanted to talk about individual vehicles, you would use another noun, such as:

• aŭtoj = cars
• veturiloj = vehicles

But trafiko as a general concept is singular here.

It already agrees.

In Esperanto, adjectives agree with the nouns they describe in number and case.

Here:

• trafiko is singular and not accusative
• so the adjective is also singular and not accusative: granda

If the noun were plural, the adjective would also be plural:

• La aŭtoj estas grandaj. = The cars are big.

If the noun were accusative, the adjective would also take -n:

• Mi vidas grandan aŭton. = I see a big car.

So granda is exactly the right form for trafiko.

The commas help separate the clauses.

This sentence has two main parts joined by sed = but:

• Poste mi iras al la haltejo
• sed la trafiko estas tiel granda, ke la aŭtobuso malfruas

Then inside the second part, ke introduces a subordinate clause:

• ke la aŭtobuso malfruas

In Esperanto, a comma before ke is standard and very common. A comma before sed is also normal when it joins two clauses.

So the punctuation here is quite natural and helps make the structure clear.