La peto enhavas informojn pri identeco kaj nacieco.

Because it has two endings added to the root:

• -o = noun
• -j = plural
• -n = accusative, marking the direct object

So:

• informo = a piece of information
• informoj = pieces of information / information
• informojn = the direct object, information

In this sentence, the request contains the information, so informojn is the thing being contained.

Because informojn is the direct object of the verb enhavas.

• La peto enhavas informojn = The request contains information

But identeco and nacieco come after pri, and nouns after a preposition normally do not take -n.

So:

• informojn = direct object
• pri identeco kaj nacieco = about identity and nationality

Pri usually means about, concerning, or regarding.

So:

• informojn pri identeco kaj nacieco = information about identity and nationality

This is very natural Esperanto. An English speaker might wonder whether some other preposition could be used, but pri is the standard choice for the topic or subject matter of information, speech, writing, and so on.

They are built with the suffix -ec-, which makes an abstract noun meaning a quality, state, or condition.

• identa = identical

• identeco = identity

• nacia = national
• nacieco = nationality

This suffix is often similar to English -ity, -ness, or sometimes -hood, depending on the word.

A learner should notice that Esperanto often builds abstract nouns very regularly like this.

Because Esperanto often leaves out the article when speaking about something in a general sense.

Here, the sentence means the request contains information about identity and nationality as topics, not necessarily the specific identity and the specific nationality in a heavily emphasized way.

Using la would be possible in some contexts, but without it the sentence sounds broad and natural.

Havas means has.
Enhavas means contains.

The prefix en- often adds the idea of in or inside, so enhavi is literally something like to have inside.

So:

• La peto havas informojn would sound more like The request has information
• La peto enhavas informojn more clearly means The request contains information

In this sentence, enhavas is the better word.

Because -as is the present-tense ending for verbs in Esperanto.

• enhavi = to contain
• enhavas = contains / is containing

Esperanto verbs do not change according to person or number, so the same form is used with mi, vi, li, ŝi, ĝi, ni, ili, and so on, as long as the tense is present.

Yes, Esperanto word order is fairly flexible, but this sentence uses the most neutral and natural order:

• La peto = subject
• enhavas = verb
• informojn = object
• pri identeco kaj nacieco = prepositional phrase

You could move parts around for emphasis, but the standard order is easiest to understand. For learners, this version is the best model.

In Esperanto, informo is countable much more easily than English information. So informoj often corresponds to English information even when English treats it as uncountable.

That means informojn here is perfectly normal, even if the most natural English translation uses singular information rather than informations.

A rough pronunciation is:

la PE-to en-HA-vas in-for-MOYN pree i-den-ti-TE-tso kai na-tsi-E-tso

A few helpful points:

• j sounds like English y
• c sounds like ts
• stress is always on the second-to-last syllable:
  • PE-to
  • en-HA-vas
  • in-for-MOJN
  • i-den-ti-TE-co
  • na-ci-E-co

That regular stress pattern is one of the nice things about Esperanto.