Uxor dicit aliquem ante portam stare; maritus autem dicit neminem intrare posse.

Because after dicit in this sentence, Latin is using indirect statement (also called the accusative-and-infinitive construction).

So instead of saying:

• The wife says: "Someone is standing..."

Latin says:

• Uxor dicit aliquem ... stare

Literally, that is something like:

• The wife says someone to be standing...

In this construction:

• the subject of the reported statement goes into the accusative
• the verb of the reported statement goes into the infinitive

So:

• aliquem = the person said to be standing
• neminem = the person said to be able to enter

Even though they are the logical subjects of stare and intrare posse, grammatically they appear in the accusative because of the indirect statement construction.

Yes. It is the very common Latin construction called indirect statement.

Its usual pattern is:

• verb of saying/thinking/perceiving
  • accusative subject
    • infinitive

Here:

• dicit = says
• aliquem = accusative subject of the reported statement
• stare = infinitive

And in the second half:

• dicit
• neminem
• intrare posse

So both halves of the sentence use the same pattern.

English often uses that:

• The wife says that someone is standing before the gate.
• The husband says that no one can enter.

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

Because in indirect statement, Latin normally changes the reported verb into an infinitive.

So if the direct statement were something like:

• Aliquis ante portam stat = Someone is standing before the gate

then after dicit it becomes:

• aliquem ante portam stare

Likewise:

• Nemo intrare potest = No one can enter

becomes:

• neminem intrare posse

So the infinitives are there because the statements are being reported, not presented directly.

Because posse means to be able, and it normally takes another infinitive with it.

So:

• intrare = to enter
• posse = to be able

Together:

• intrare posse = to be able to enter

This is not unusual at all. It is just like English to be able to enter.

And because the whole thing is inside indirect statement, posse is also in the infinitive:

• direct statement: nemo intrare potest
• indirect statement: neminem intrare posse

Because nemo is the nominative form, while neminem is the accusative form.

In a normal sentence, you would say:

• Nemo intrat = No one enters
• Nemo intrare potest = No one can enter

But after dicit, Latin uses indirect statement, so the subject of the reported clause must be accusative:

• neminem intrare posse

So the change from nemo to neminem happens for the same reason that aliquis would become aliquem in this construction.

Autem usually means however, but, or on the other hand.

Here it contrasts the husband’s statement with the wife’s statement:

• Uxor dicit ... ; maritus autem dicit ...
• The wife says ... ; the husband, however, says ...

A useful thing to remember is that autem is often postpositive, meaning it tends to come after the first word or phrase of its clause rather than standing first.

So Latin prefers:

• maritus autem dicit

rather than:

• autem maritus dicit

Here ante is a preposition meaning before or in front of, and it takes the accusative.

So:

• porta = gate (nominative/ablative form)
• portam = gate in the accusative

Thus:

• ante portam = before the gate / in front of the gate

This is simply the normal construction of ante with the accusative.

Both are nominative singular and are the subjects of dicit.

So:

• uxor dicit = the wife says
• maritus autem dicit = the husband, however, says

They are straightforward subjects of the main verbs in the sentence.

You figure that out from the accusative subject + infinitive pattern.

In the first clause:

• aliquem ... stare
• someone is the one standing

In the second clause:

• neminem intrare posse
• no one is the one able to enter

So although aliquem and neminem are accusative, they are still the logical subjects of the infinitives.

That is one of the most important things to get used to in Latin indirect statement: the subject of the reported action is accusative, not nominative.

Because Classical Latin usually does not need a separate word like English that in this construction.

English says:

• The wife says that someone is standing...

Latin usually says:

• Uxor dicit aliquem ... stare

So the idea of that is built into the grammar of the accusative + infinitive construction rather than expressed by a separate conjunction.

In context, it often feels like to be standing.

Latin stare basically means to stand or to be standing, and in indirect statement the present infinitive usually shows action happening at the same time as the main verb.

So:

• uxor dicit aliquem ante portam stare

means that the wife says the person is standing there at that time.

Similarly:

• neminem intrare posse

means the husband says that no one can enter at that time.

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

For example, Latin could rearrange parts of this sentence and still keep the same basic meaning, as long as the forms remain clear.

However, the given word order is natural and readable:

• Uxor dicit aliquem ante portam stare
• maritus autem dicit neminem intrare posse

A learner should still pay close attention to the endings, not just to position:

• uxor, maritus = nominative subjects
• aliquem, neminem = accusative subjects of the infinitives
• portam = accusative after ante

Because Latin does not have articles like English the and a/an.

So:

• uxor can mean wife or the wife
• maritus can mean husband or the husband
• porta can mean gate or the gate
• aliquem can mean someone or a certain person, depending on context

English has to choose an article when translating, but Latin usually leaves that to the context.

Aliquem comes from aliquis and usually means someone or anyone/someone or other in a fairly indefinite way.

So here:

• aliquem = someone

By contrast, quidam often means a certain person, sometimes with the nuance that the speaker has a more specific individual in mind.

So if Latin had used quendam instead of aliquem, it could suggest:

• a certain man/person

But aliquem is the more ordinary choice for someone in this sentence.

It would be something like:

• Nemo intrare potest.

That is the direct version:

• No one can enter.

Then when it becomes indirect after dicit, Latin changes it to:

• neminem intrare posse

The same transformation happens in the first clause:

• direct: Aliquis ante portam stat.
• indirect: aliquem ante portam stare

This is a very useful exercise for understanding indirect statement: try converting between direct and indirect versions.