Viginti cives oratorem in contione audiunt.

Yes, cives can be either nominative plural or accusative plural, so by itself it is ambiguous.

In this sentence, we understand cives as the subject because:

• audiunt means they hear / listen to
• oratorem is clearly accusative singular, so it is the direct object
• that leaves cives as the most natural subject: the citizens hear the orator

So Latin learners often have to use the whole sentence, not just one word ending, to determine the grammar.

Oratorem is accusative singular.

You can tell because it is from orator, oratoris, a third-declension noun, and its accusative singular ends in -em.

Here it is the direct object of audiunt, because it answers the question whom do the citizens hear?
Answer: the orator.

Because in with the ablative usually means in or on in the sense of location.

So:

• in contione = in the assembly / at the public meeting

This is different from in with the accusative, which often shows motion into something.

A useful contrast is:

• in contione = in the assembly
• in contionem = into the assembly

Here the sentence describes where the hearing takes place, so the ablative is used.

The dictionary form is contio, contionis, a feminine third-declension noun.

So contione is the ablative singular form.

A learner may find this surprising because the nominative contio looks quite different from contione, but that is normal for many third-declension nouns.

Because viginti means twenty, and numerals like this are usually indeclinable in Latin.

That means the form stays the same regardless of gender, number, or case.

So you can have:

• viginti cives = twenty citizens
• viginti viros = twenty men
• viginti feminas = twenty women

The noun changes as needed, but viginti does not.

Latin word order is much more flexible than English word order because Latin uses case endings to show grammatical function.

Putting the verb at the end is extremely common in Latin, especially in straightforward prose.

So:

• Viginti cives oratorem in contione audiunt

is a very normal Latin order.

English relies much more on position, but Latin can move words around for emphasis, style, or rhythm without changing the basic meaning.

Audiunt is:

• present tense
• active voice
• indicative mood
• third person plural

It comes from audio, audire, meaning to hear or to listen to.

So audiunt means:

• they hear
• or, depending on context, they are listening to

Because it is third person plural, it matches cives, which is plural.

Latin has no articles equivalent to English the or a/an.

So a noun like cives can mean:

• citizens
• the citizens

and oratorem can mean:

• an orator
• the orator

The exact sense depends on context. In many teaching sentences, English uses the because it sounds more natural, but Latin does not need a separate word for it.

Yes, very often it could.

For example, Latin could also say things like:

• Oratorem viginti cives in contione audiunt
• In contione viginti cives oratorem audiunt

These still mean basically the same thing: Twenty citizens hear the orator in the assembly.

However, changing the order can shift emphasis:

• placing oratorem early may emphasize the orator
• placing in contione early may emphasize the setting

So word order in Latin often affects nuance more than core grammar.

It can be either, depending on context.

The verb audio basically means hear, but in many contexts, especially with a speaker, English naturally says listen to.

So in this sentence:

• hear the orator
• listen to the orator

both are reasonable.

A learner should remember that Latin does not always divide these ideas exactly the same way English does.

Because numerals commonly stand before the noun they modify.

So viginti cives is the normal way to say twenty citizens.

Latin is flexible, and the numeral could be separated from the noun in some contexts, but keeping them together is the most straightforward and easiest pattern for learners to recognize.