Cives aedilem novum creant, qui forum diligenter administrare et silentium a turba postulare debeat.

Because cives is in the nominative plural, which is the normal case for the subject.

• cives = citizens (nominative plural)
• creant = they elect/create

Latin word order is more flexible than English word order, so you identify the subject mainly by case ending, not just by position.

Because it is the direct object of creant.

• creare can mean to create, but in a political context it often means to elect or appoint
• So cives aedilem novum creant means the citizens are electing a new aedile

Since the aedile is the person being elected, aedilem is in the accusative singular.

Because novum is agreeing with aedilem.

Latin adjectives must agree with the nouns they describe in:

• gender
• number
• case

Here:

• aedilem is masculine singular accusative
• so the adjective must also be masculine singular accusative
• therefore: novum

Qui is masculine singular nominative.

It refers back to aedilem, so its:

• gender = masculine
• number = singular

But its case is determined by its job inside its own clause, not by the case of aedilem.

Here qui is the subject of debeat, so it must be nominative:

• qui ... debeat = who should / is to ...

This is a very common Latin point: a relative pronoun matches its antecedent in gender and number, but gets its case from its own clause.

Because the relative clause is not just stating a plain fact about the aedile; it expresses an intended role, expected duty, or characteristic.

So the idea is not simply:

• who does manage the forum

but more like:

• who should manage the forum
• who is supposed to manage the forum
• the kind of man who should manage the forum

Many grammars describe this as a relative clause of characteristic, or at least as a purpose-like use of the relative clause. The subjunctive helps give that nuance.

Latin often uses a relative pronoun + subjunctive when the idea of purpose or intended function is closely tied to a noun.

So instead of saying something like:

• They elect a new aedile in order that he may...

Latin can say:

• They elect a new aedile who is to...

That makes the duty feel like part of the description of the person being chosen.

Because they depend on debeat.

With debeo, Latin normally uses an infinitive to express what someone ought to do:

• debeat administrare = he should manage
• debeat postulare = he should demand

These are often called complementary infinitives, because they complete the meaning of debeat.

Because forum is the direct object of administrare.

• administrare forum = to manage the forum

In Latin, a direct object commonly appears in the accusative without any preposition. English often works the same way:

• manage the forum
• see the man
• build a house

Because they do different jobs in the sentence.

• silentium is the direct object of postulare
  • postulare silentium = to demand silence
• a turba means from the crowd
  • turba is in the ablative because it follows the preposition a

So:

• what is demanded? → silentium
• from whom is it demanded? → a turba

Both a and ab mean from.

A common beginner rule is:

• a before consonants
• ab before vowels or h

Since turba begins with t, a turba is the expected form. In real Latin usage, there is some flexibility, but this is the normal pattern to learn first.

Diligenter is an adverb, meaning carefully or diligently.

It modifies the verb administrare, telling us how the forum is to be managed.

Compare:

• diligens = careful / diligent (adjective, describing a noun)
• diligenter = carefully / diligently (adverb, describing a verb)

So here Latin needs the adverb, because it is modifying the action of managing.

Both are possible in Latin.

Latin word order is flexible, and adjective placement can vary for style, emphasis, or rhythm. In this sentence, aedilem novum is a perfectly normal order.

A learner should not assume that adjective position works exactly like English. The key thing is still agreement:

• aedilem and novum belong together because they match in case, number, and gender.

A helpful breakdown is:

• Cives = subject
• aedilem novum = direct object
• creant = main verb
• qui ... debeat = relative clause describing aedilem
  • qui = subject of the relative clause
  • forum = object of administrare
  • diligenter = adverb
  • administrare = infinitive with debeat
  • silentium = object of postulare
  • a turba = prepositional phrase, from the crowd
  • postulare = infinitive with debeat
  • debeat = subjunctive verb giving the sense of duty or intended role

So the structure is basically:

• The citizens elect a new aedile
• who should manage the forum carefully and demand silence from the crowd