Ni ŝanĝis la dekoracion antaŭ la provludo.

No. In Esperanto, verbs do not change for person or number.

So:

• mi ŝanĝis = I changed
• vi ŝanĝis = you changed
• li/ŝi ŝanĝis = he/she changed
• ni ŝanĝis = we changed

The subject pronoun tells you who did the action; the verb ending tells you the tense.

The ending -is marks the past tense.

So ŝanĝis = changed.

Esperanto tense endings are very regular:

• -as = present
• -is = past
• -os = future

So you can compare:

• ŝanĝas = changes / is changing
• ŝanĝis = changed
• ŝanĝos = will change

The -n marks the direct object. It shows what was changed.

• dekoracio = decoration
• dekoracion = the decoration, as the object of the verb

Since ŝanĝi is a transitive verb, it acts on something. In this sentence, the thing being changed is la dekoracion.

Because la provludo is part of the prepositional phrase antaŭ la provludo.

After a preposition like antaŭ, the noun normally does not take -n just because it follows the preposition. The preposition already shows the relationship.

So:

• la dekoracion = direct object → needs -n
• antaŭ la provludo = prepositional phrase → no -n

Yes. Antaŭ can refer to either:

• time: before
• space: in front of

In this sentence it is clearly about time, so it means before:

• antaŭ la provludo = before the rehearsal

In another sentence, it could be spatial:

• Li staras antaŭ la domo = He is standing in front of the house.

Because there are two separate definite nouns:

• la dekoracion
• la provludo

Esperanto la means the and does not change for gender, number, or case.

So even though dekoracion has -n, the article stays just la, not anything else.

Yes. Esperanto word order is fairly flexible, especially because the -n ending helps show the object.

The neutral order here is:

• Ni ŝanĝis la dekoracion antaŭ la provludo.

But you could also say:

• Antaŭ la provludo ni ŝanĝis la dekoracion.

That version emphasizes the time more. Both are correct.

Yes. Esperanto often builds words by combining roots.

provludo is made from:

• prov- = test, trial
• ludo = play, performance-related playing

So provludo literally suggests something like a trial performance, which is why it means rehearsal.

This kind of word-building is very common in Esperanto.

A few useful pronunciation points:

• ŝ sounds like sh
• ĝ sounds like the j in jam
• ŭ is a short glide, used in combinations like aŭ

So:

• ŝanĝis ≈ SHAHN-jees
• antaŭ ≈ AHN-tow

Stress in Esperanto normally falls on the second-to-last syllable:

• ŝANĝis
• anTAŬ
• de-ko-ra-CI-on
• prov-LU-do

In this context, because the sentence mentions a rehearsal, dekoracio will often be understood as stage decoration, the set, or scenery.

The Esperanto word itself can be broader than a single English translation. Context tells you which English meaning fits best.

So here, depending on the situation, English might naturally say:

• the decoration
• the set
• the scenery

Esperanto often uses the simple past -is where English might use either changed or had changed. Context usually makes the time relationship clear.

So Ni ŝanĝis la dekoracion antaŭ la provludo is perfectly natural.

If you really need to stress an earlier completed action, Esperanto can do that more explicitly, but in ordinary language the simple past is usually enough.