Antaŭhieraŭ la profesorino sendis retpoŝton, ĉar ŝi volis ŝanĝi la horon de la prelego.

Antaŭhieraŭ means the day before yesterday.

It is built from:

• antaŭ = before
• hieraŭ = yesterday

So Esperanto often makes words in a very logical, buildable way.

La means the.

So la profesorino means the professor or more specifically the female professor. It suggests that the speaker has a particular professor in mind, not just any professor.

Esperanto:

• has la for the
• has no indefinite article for a/an

So:

• profesorino = a female professor / female professor
• la profesorino = the female professor

The ending -in- is the Esperanto suffix for female.

So:

• profesoro = professor
• profesorino = female professor

This is a very common pattern in Esperanto:

• patro = father/parent in older usage, but usually father
• patrino = mother
• frato = brother
• fratino = sister

So profesorino is not a completely separate word to memorize; it is built from profesoro + -in-.

-is is the Esperanto ending for the past tense.

So:

• sendi = to send
• sendas = sends / is sending
• sendis = sent
• sendos = will send

Because the sentence talks about something that happened in the past, Esperanto uses sendis.

The -n marks the direct object.

Here, the thing that was sent is the email, so retpoŝton is the direct object of sendis.

Compare:

• La profesorino sendis retpoŝton. = The professor sent an email.
• Retpoŝto alvenis. = An email arrived.

In the second sentence, retpoŝto is the subject, so there is no -n.

This -n ending is one of the most important features of Esperanto grammar.

Because Esperanto does not have an indefinite article.

English distinguishes:

• a/an email
• the email

Esperanto only has:

• retpoŝto / retpoŝton = an email / email
• la retpoŝto / la retpoŝton = the email

So sendis retpoŝton naturally means sent an email.

Ĉar means because.

It introduces the reason:

• La profesorino sendis retpoŝton, ĉar ŝi volis ŝanĝi la horon...
• The professor sent an email, because she wanted to change the time...

Like English because, it introduces a clause explaining why something happened.

Yes, in this sentence ŝi means she, and it naturally refers back to la profesorino.

That is especially clear because:

• profesorino is feminine
• ŝi is the feminine pronoun she

So the sentence is tightly connected:

• la profesorino = the female professor
• ŝi = she

This is like English wanted to change.

• volis = wanted
• ŝanĝi = to change

Esperanto uses the infinitive ending -i for verbs in their basic form:

• sendi = to send
• voli = to want
• ŝanĝi = to change

So:

• ŝi volis ŝanĝi = she wanted to change

Unlike English, Esperanto does not need a separate word like to before the infinitive. The infinitive ending -i already shows that meaning.

Ŝanĝi la horon means to change the time.

Literally:

• ŝanĝi = change
• la horon = the time / the hour

Even though horo often means hour, in context it can also mean the scheduled time of something.

So here it means the time when the lecture is supposed to happen.

Also, horon has -n because it is the direct object of ŝanĝi:

• she wanted to change what?
• the time

De usually means of, from, or sometimes shows relationship or possession, depending on context.

Here:

• la horo de la prelego = the time of the lecture

So de la prelego tells us which time: not just any time, but the time belonging to or associated with the lecture.

This is a very common Esperanto structure:

• la pordo de la domo = the door of the house
• la nomo de la urbo = the name of the city
• la horo de la prelego = the time of the lecture

Prelego is the noun lecture.

It comes from:

• prelegi = to lecture / give a lecture
• prelego = a lecture

This shows another basic Esperanto pattern:

• verbs often end in -i
• nouns often end in -o

So:

• prelegi = to lecture
• prelego = lecture

Yes, Esperanto word order is fairly flexible, but this sentence uses the most natural, straightforward order.

Normal structure here:

• Antaŭhieraŭ = time
• la profesorino = subject
• sendis = verb
• retpoŝton = object
• ĉar... = reason clause

Because Esperanto marks the direct object with -n, the language does not depend on word order as much as English does.

For example, retpoŝton la profesorino sendis would still be understandable, because retpoŝton has -n. But it sounds more marked or stylistic. The version in the sentence is the most neutral.

In this sentence:

• ŝ sounds like English sh

  • ŝi sounds like she
  • poŝto sounds roughly like poshto

• ĉ sounds like English ch

  • ĉar sounds like char in chart

• ŭ is a short w-like sound and appears in aŭ

  • antaŭ sounds roughly like an-tow
  • hieraŭ ends with the same aŭ sound

So:

• Antaŭhieraŭ has two aŭ sounds
• ŝi has sh
• ĉar has ch

More or less, yes:

• Antaŭhieraŭ = the day before yesterday
• la profesorino = the female professor / the professor
• sendis = sent
• retpoŝton = an email
• ĉar = because
• ŝi = she
• volis = wanted
• ŝanĝi = to change
• la horon = the time
• de la prelego = of the lecture

A very literal English version would be:

The day before yesterday the female professor sent an email because she wanted to change the time of the lecture.

So the Esperanto sentence is quite close to English in structure, but with clearer grammatical endings.