Praefectus novus ab imperatore creatus est.

Because praefectus is in the nominative singular, which is the case normally used for the subject of a finite verb in Latin.

Here, praefectus means prefect (or sometimes commander/governor, depending on context), and it is the person being talked about.

You can also tell it is the subject because creatus est is singular, and creatus matches praefectus in gender, number, and case.

Novus is an adjective meaning new, and it modifies praefectus.

It agrees with praefectus in:

• case: nominative
• number: singular
• gender: masculine

So:

• praefectus = prefect
• novus = new

Together: the new prefect

Latin word order is much more flexible than English word order.

Both of these can mean the same thing:

• praefectus novus
• novus praefectus

So the adjective does not have to come before the noun. In many Latin sentences, adjective position depends on style, emphasis, rhythm, or author preference rather than a strict rule like in English.

In this sentence, praefectus novus still simply means the new prefect.

Because this is a passive sentence, and the person doing the action is expressed with ab + ablative when the agent is a person.

So:

• ab imperatore = by the emperor

This is called the ablative of personal agent.

Latin commonly uses:

• a/ab + ablative for a person doing the action in a passive sentence
• a plain ablative without ab more often for an instrument or means

So ab imperatore tells you that the emperor is the one who appointed/created him.

It is in the ablative singular because it follows ab, and ab takes the ablative.

Also, in a passive sentence, ab + ablative is the normal way to express the personal agent:

• ab imperatore = by the emperor

The base form is imperator. Here it appears as imperatore because the grammar requires the ablative singular.

Creatus est is the perfect passive indicative, third person singular.

It is made of two parts:

• creatus = perfect passive participle of creare
• est = is, from esse

Together they mean:

• was created
• more naturally in context, often was appointed

This is a very common Latin passive construction:

• participial form
  • form of esse

Because the subject is masculine singular (praefectus), the participle is also masculine singular: creatus.

Because Latin forms the perfect passive differently from the present/imperfect/future passive.

For many passive tenses, Latin uses single-word forms, for example:

• creatur = he is being created / he is appointed
• creabatur = he was being created / was being appointed

But the perfect passive is built with:

• the perfect passive participle
• plus a form of esse

So:

• creatus est = he was created / was appointed

There is no normal classical form creavitur for this meaning.

Literally, yes: it comes from creare, which can mean create, produce, elect, or appoint.

But in political or official contexts, creare often means:

• appoint
• elect
• make someone into an office-holder

So with praefectus, the most natural English is usually:

• was appointed prefect or, if the office is already understood,
• the new prefect was appointed by the emperor

So even though created is the literal root meaning, appointed is often the better translation in context.

Yes. The Latin perfect often covers both ideas that English separates:

• simple past: was appointed
• present perfect: has been appointed

Which English version sounds best depends on context.

So Praefectus novus ab imperatore creatus est could be understood as:

• The new prefect was appointed by the emperor or
• The new prefect has been appointed by the emperor

They are:

• praefectus, -i (masculine noun) = prefect, commander, governor
• novus, -a, -um (adjective) = new
• imperator, imperatoris (masculine noun) = emperor, commander
• creo, creare, creavi, creatus (verb) = create, appoint, elect
• sum, esse, fui, futurus (verb) = be
• ab (preposition with ablative) = by, from

Knowing dictionary forms helps you identify why the words look the way they do in the sentence.

Not as much as in English. Latin relies heavily on word endings rather than fixed word order.

In this sentence:

• praefectus is nominative, so it is the subject
• imperatore is ablative after ab, so it is the agent
• creatus est is the verb phrase

Because the endings show the grammar, Latin can move words around for emphasis. For example, these would still mean essentially the same thing:

• Praefectus novus ab imperatore creatus est.
• Ab imperatore praefectus novus creatus est.
• Novus praefectus creatus est ab imperatore.

The exact nuance may shift slightly, but the core meaning remains the same.

Because creatus is nominative singular masculine, and praefectus is also nominative singular masculine.

But imperatore is ablative singular masculine, so it does not match creatus in case.

In a perfect passive construction, the participle agrees with the subject, not with the agent:

• subject: praefectus
• agent: ab imperatore

So creatus must go with praefectus.

Yes, that is the corresponding active version of the same basic idea.

Passive:

• Praefectus novus ab imperatore creatus est.
• The new prefect was appointed by the emperor.

Active:

• Imperator praefectum novum creavit.
• The emperor appointed the new prefect.

This is a useful way to check your understanding:

• the passive subject becomes the active direct object
• ab imperatore becomes the active subject
• creatus est becomes creavit in the active perfect