Ni ricevis oficialan respondon.

The ending -is marks the past tense in Esperanto.

So ricevis = the verb root ricev- + -is, meaning that the receiving happened in the past.

A useful pattern is:

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

So:

• Ni ricevas = we receive / we are receiving
• Ni ricevis = we received
• Ni ricevos = we will receive

The -n shows the direct object of the verb.

In this sentence, ni is the subject doing the action, and respondon is the thing that was received, so it gets the accusative ending -n.

• Ni ricevis respondon = We received a response.

This is a very common Esperanto pattern:

• subject with no special ending
• direct object with -n

Because adjectives must agree with the nouns they describe.

Since respondon is:

• singular
• accusative

the adjective describing it must match:

• oficiala respondo = an official response
• oficialan respondon = an official response (as direct object)

So the -n is not only on the noun; it also appears on the adjective that belongs with it.

The basic dictionary form is respondo.

Here is the breakdown:

• respondo = response, answer
• respondon = response, answer + direct object -n

So if you look it up in a dictionary, you would look for respondo, not respondon.

Esperanto does not have an indefinite article like English a/an.

So:

• respondo can mean a response
• la respondo means the response

That means oficialan respondon naturally means an official response unless the context makes it definite.

Esperanto only has one article: la.

Not completely. Esperanto word order is fairly flexible because the -n helps show what the object is.

The normal, neutral order is:

• Ni ricevis oficialan respondon.

But other orders are possible for emphasis, such as:

• Oficialan respondon ni ricevis.

That said, for learners, the standard subject–verb–object order is usually the safest and most natural choice.

Yes. In Esperanto, adjectives can come before or after the noun.

So both are possible:

• oficialan respondon
• respondon oficialan

But putting the adjective before the noun is usually more common and more neutral, especially for beginners.

So the sentence as written sounds very natural.

Usually, you should keep ni.

In Esperanto, the verb form ricevis does not show the person by itself. It can mean:

• I received
• you received
• he received
• she received
• we received
• they received

So the pronoun is normally included unless the subject is already very clear from context.

That is different from some languages where the verb ending already tells you the person.

The dictionary form is ricevi, which means to receive.

Breakdown:

• ricevi = to receive
• ricevas = receive / am receiving / are receiving
• ricevis = received
• ricevos = will receive

So when learning vocabulary, it helps to identify the root and infinitive form:

• root: ricev-
• infinitive: ricevi

No. Respondo is a noun, not a verb.

• respondo = response, answer
• respondi = to respond, to answer

In this sentence, the noun is used:

• Ni ricevis oficialan respondon.
  We received an official response.

If you wanted a verb instead, the sentence structure would be different.