La koruso kantas sen instrumento.

La is the definite article, meaning the.

So la koruso means the choir.
If you said just koruso, it would sound more general or dictionary-like, not a specific choir already known from context.

Because koruso is a collective singular noun. It names the group as one unit.

This is similar to English the choir sings. Even though many people are involved, the noun itself is singular.

If you wanted to talk about the individual singers, you could use la korusanoj or another expression referring to the members.

The ending -as marks the present tense in Esperanto.

So:

• kantas = sings / is singing
• kantis = sang
• kantos = will sing

Here, La koruso kantas means The choir sings / is singing.

The -n ending usually marks the direct object in Esperanto.

But in this sentence:

• la koruso is the subject
• kantas is the verb
• sen instrumento is a prepositional phrase

There is no direct object, so no accusative -n is needed.

Also, sen is a preposition, and prepositions normally take the basic form of the noun, not -n.

Sen means without.

It is a preposition, so it introduces a phrase:

• sen instrumento = without an instrument

Just like English without, it shows absence or lack of something.

Other examples:

• sen akvo = without water
• sen helpo = without help
• sen muziko = without music

Because instrumento is the object of the preposition sen, not the direct object of the verb.

In Esperanto, nouns after prepositions normally stay in the basic form:

• kun amiko = with a friend
• sen mono = without money
• por infano = for a child

So sen instrumento is correct.

Esperanto has no indefinite article. There is only la for the.

So:

• instrumento can mean an instrument or instrument
• la instrumento means the instrument

That is why sen instrumento naturally means without an instrument.

Yes, that is possible, but it gives a slightly different feel.

• sen instrumento = without an instrument / without instrumental accompaniment
• sen instrumentoj = without instruments

The singular can sound more general or idiomatic, while the plural emphasizes that there are no instruments involved at all.

Both can work depending on context.

Yes. Kanti can be used intransitively, meaning simply to sing.

So La koruso kantas is a complete sentence: The choir sings.

But kanti can also take an object when you say what is being sung:

• La koruso kantas himnon. = The choir sings a hymn.
• Ŝi kantas kanton. = She sings a song.

In your sentence, the focus is on the act of singing, not on a specific song.

Yes, Esperanto word order is fairly flexible, though the most neutral order is subject + verb + other information.

So the normal version is:

• La koruso kantas sen instrumento.

You could also say:

• Sen instrumento la koruso kantas.

That puts more emphasis on without an instrument.

Because Esperanto marks grammar clearly, word order can shift for style or emphasis more easily than in English.

In this sentence, yes, that is the natural interpretation because of the context: a choir singing.

By itself, instrumento can mean instrument, tool, or implement in a broader sense. But next to koruso and kantas, most readers will understand it as a musical instrument.

If you wanted to be extra explicit, you could say muzikinstrumento.

A simple pronunciation guide:

• La ≈ lah
• koruso ≈ ko-ROO-so
• kantas ≈ KAHN-tahs
• sen ≈ sen
• instrumento ≈ in-stru-MEN-to

A few useful pronunciation points:

• Esperanto stress is almost always on the second-to-last syllable
• each letter is pronounced consistently
• o is always a clear o
• a is always a clear ah

So the stress falls on:

• koRUso
• KANtas
• instruMENto