Pater dicit vinum bonum ex Hispania saepe Romam portari.

Because after dicit (“says”), Latin often uses indirect statement.

In English, we usually say Father says that good wine is often carried...
In Latin, instead of using that + a finite verb, you usually use:

• an accusative subject
• plus an infinitive

So:

• dicit = “he says”
• vinum bonum ... portari = “good wine ... to be carried / is carried”

This is a very common Latin construction called the accusative-and-infinitive construction.

Because in an indirect statement, the subject of the infinitive goes into the accusative.

Here, the thing being said is:

• vinum bonum ... portari = “good wine ... is carried”

Even though vinum bonum is the logical subject of portari, Latin puts it in the accusative because it is the subject of an infinitive in indirect statement.

So:

• vinum bonum = accusative singular
• it functions as the subject of portari

Portari is the present passive infinitive of portare.

• portare = “to carry”
• portari = “to be carried”

That means the sentence is not saying that the wine carries something else. It is saying that the wine is carried / transported.

So the idea is:

• Father says [that] good wine is often transported to Rome from Spain.

Portari is a present infinitive, specifically a present passive infinitive.

In indirect statement, the present infinitive usually shows action happening at the same time as the main verb.

So:

• Pater dicit ... portari = “Father says ... is being carried / is carried”

In smoother English, this often becomes simply “Father says that good wine is often transported...”

Because bonum is an adjective agreeing with vinum.

• vinum is neuter singular accusative
• so the adjective must also be neuter singular accusative
• therefore: bonum

Agreement in Latin means adjectives match their nouns in:

• gender
• number
• case

So:

• vinum bonum = “good wine”

Because Latin usually does not need a separate word meaning that in this kind of sentence.

English says:

• Father says that good wine...

Latin usually says:

• Pater dicit vinum bonum... portari

The accusative + infinitive construction does the job that that-clause does in English.

Because names of cities often use the accusative without a preposition to show motion toward a place.

So:

• Romam = “to Rome”

This is a special and very common Latin idiom with towns and cities.

Compare:

• Romam = “to Rome”
• Romae = “at Rome / in Rome” (in another construction)
• Roma = “from Rome” (in another construction)

Because Latin treats these two ideas differently here:

• Romam shows motion toward a city, so no preposition is needed.
• ex Hispania means motion out of / from Spain, and with countries or larger regions Latin normally uses a preposition such as ex or ab.

So:

• Romam = “to Rome”
• ex Hispania = “from Spain”

Also, Hispania is in the ablative after ex.

It is ablative singular because it follows the preposition ex.

• ex = “out of, from”
• prepositions like ex take the ablative

So:

• ex Hispania = “from Spain”

Saepe means often, and it modifies the verbal idea portari.

So the sense is:

• good wine is often carried
• not just “good wine” in some special way

Latin adverbs can often move around fairly freely, so saepe does not have to stand right next to the verb to modify it.

Latin word order is more flexible than English word order, because the endings show the grammatical relationships.

So this sentence could be rearranged in various ways without changing the basic meaning, for example:

• Pater dicit vinum bonum ex Hispania saepe Romam portari.
• Pater dicit saepe vinum bonum ex Hispania Romam portari.
• Vinum bonum ex Hispania Romam saepe portari pater dicit.

The basic meaning stays the same, though different word orders can give different emphasis.

Because Latin has no articles.

So pater can mean:

• father
• the father
• a father

and vinum bonum can mean:

• good wine
• the good wine
• sometimes even a good wine, depending on context

You decide which English article to use from the context.

Yes. Very often, a phrase like vinum bonum can be understood generally as good wine.

Without articles, Latin does not force the distinction between:

• good wine
• the good wine

The context tells you whether it is general or specific.

The sentence does not say.

Because portari is passive, we are told what happens to the wine, not who does it.

So the meaning is simply:

• good wine is often carried / transported to Rome from Spain

If Latin wanted to say who was doing it, it could add an agent, for example with ab + ablative in an appropriate context.

Because pater is the subject of the main verb dicit.

So the sentence is built like this:

• Pater = subject of dicit
• dicit = main verb
• vinum bonum ex Hispania saepe Romam portari = the indirect statement, “that good wine is often carried...”

So there are really two layers:

1. Father says
2. good wine is often carried to Rome from Spain

Yes. That is often the most natural English here.

• portare basically means to carry
• but in many contexts, especially with goods and trade, transport is a very good translation

So a natural translation is:

• Father says that good wine is often transported to Rome from Spain.

That is probably smoother English than a very literal carried.