Nauta narrat oleum ex Africa saepe ad Italiam vehi.

The main finite verb is narrat = he/she tells, relates, reports.

The form vehi is not another main verb. It is an infinitive, and it belongs to an indirect statement after narrat.

So the sentence is built like this:

• Nauta narrat = The sailor reports
• oleum ... vehi = that oil is carried

Because this is an indirect statement.

In Latin, after verbs like narrat, dicit, putat, and similar verbs of saying or thinking, English often uses that, but Latin usually uses:

• accusative noun
• • infinitive

So oleum is the subject of the infinitive vehi, but in Latin that subject goes into the accusative case.

So:

• oleum vehi = that oil is being carried

Even though oil is the logical subject of is being carried, Latin puts it in the accusative because of the construction.

Yes.

English says:

• The sailor reports that oil is often carried from Africa to Italy.

Latin usually does not use a separate word for that in this kind of sentence. Instead, it uses the accusative + infinitive construction:

• narrat oleum ... vehi

So the idea of that is built into the grammar, not expressed by a separate word.

Vehi is the present passive infinitive of veho.

Basic idea:

• veho = I carry / transport
• vehi = to be carried / to be transported

Here it means:

• oleum ... vehi = oil to be carried / oil is carried

In this sentence, the most natural English is:

• that oil is often carried from Africa to Italy

The present infinitive in indirect statement usually shows action happening at the same time as the main verb:

• narrat ... vehi = he reports that it is being carried / is carried

Because the sentence focuses on oil as the thing being transported, not on the people transporting it.

Compare:

• oleum vehi = that oil is carried
• nautas oleum vehere = that sailors carry oil

In your sentence, oil is the center of the reported action, so the passive is the natural choice.

They show movement from one place to another.

• ex Africa = out of / from Africa
• ad Italiam = to Italy / toward Italy

The prepositions require different cases:

• ex takes the ablative
• ad takes the accusative

So:

• Africa here is ablative singular: Africā if macrons are written
• Italiam is accusative singular

This is very common Latin usage:

• ex
  • ablative = from
• ad
  • accusative = to, toward

Saepe means often. It modifies the action vehi.

Latin word order is more flexible than English word order, so saepe can move around more freely than often can in English. Here it sits between the place phrases and the infinitive:

• oleum ex Africa saepe ad Italiam vehi

That means roughly:

• that oil is often carried from Africa to Italy

Its position is normal and does not cause a major change in meaning. It mainly affects emphasis slightly, not the basic sense.

Yes, nauta is a first-declension noun, but it is usually masculine because it refers to a person whose role was traditionally male in Latin usage.

So:

• nauta = sailor
• nominative singular: nauta
• genitive singular: nautae

This is one of several common first-declension masculine nouns, especially words for occupations or social roles, such as:

• agricola = farmer
• poeta = poet
• nauta = sailor

So the form looks first-declension, but the gender is masculine.

Not really, not in the normal analysis of this sentence.

The sentence is best understood as:

• narrat = reports
• oleum ... vehi = the content of what is reported

So oleum is not simply the thing he reports. It is the accusative subject of the infinitive vehi.

In other words, the sailor is not just reporting oil; he is reporting that oil is often carried from Africa to Italy.

Yes. Latin word order is quite flexible.

For example, these would still express basically the same idea:

• Nauta oleum ex Africa ad Italiam saepe vehi narrat.
• Oleum ex Africa ad Italiam saepe vehi nauta narrat.
• Nauta narrat ex Africa ad Italiam oleum saepe vehi.

The grammar stays clear because the endings and constructions show the relationships.

That said, the original order is perfectly natural. Latin often places the main verb early or late depending on emphasis, and infinitives often come near the end.

Several English verbs can work:

• tells
• says
• reports
• relates

In this sentence, reports or relates can sound especially natural because narrat often has the sense of telling a story, recounting, or describing.

So a good translation is:

• The sailor reports that oil is often carried from Africa to Italy.

But The sailor says that oil is often carried from Africa to Italy is also acceptable if the context is simple.

Because classical Latin normally prefers the accusative-and-infinitive construction after verbs of saying, thinking, knowing, hearing, and perceiving.

English pattern:

• He says that oil is carried.

Latin pattern:

• Narrat oleum vehi.

So instead of a subordinate clause with its own finite verb, Latin often uses:

• an accusative noun as the subject
• an infinitive as the verb

This is one of the most important sentence patterns in Latin, and your sentence is a very standard example of it.