Flumen latum prope urbem fluit.

Because flumen is a neuter noun, and the adjective has to agree with it in gender, number, and case.

• flumen = neuter, singular, nominative
• latum = neuter, singular, nominative

The dictionary form of the adjective is latus, lata, latum = wide / broad.
Since it is describing a neuter noun, Latin uses the neuter form latum.

If the noun were masculine, you would expect latus.
If it were feminine, you would expect lata.

Flumen is nominative singular, and it is the subject of fluit.

A learner might notice that flumen could also look like an accusative form, because many neuter nouns have the same form in the nominative and accusative. But here it is understood as the subject because:

• fluit is a singular verb: he/she/it flows
• a river is what logically does the action of flowing
• prope urbem is a prepositional phrase, so urbem is not the subject

So the structure is:

• flumen latum = the wide river / a wide river
• prope urbem = near the city
• fluit = flows

Because prope takes the accusative when it is used as a preposition meaning near.

So:

• urbs = city
• urbem = accusative singular
• prope urbem = near the city

This is something English speakers often have to get used to: in Latin, many prepositions require a particular case after them, and you simply have to learn which one each preposition takes.

Here prope is a preposition meaning near.

It introduces the phrase prope urbem = near the city.

A useful point is that prope can also sometimes function as an adverb in Latin, but in this sentence it is clearly being used as a preposition because it is followed by a noun phrase, urbem.

Latin word order is much more flexible than English word order because the endings show how the words function in the sentence.

English usually prefers something like:

• The wide river flows near the city.

Latin can say:

• Flumen latum prope urbem fluit.

This is still perfectly natural Latin. The verb often comes at or near the end, though it does not have to. Because the endings already tell you what goes with what, Latin does not rely on word order as heavily as English does.

It is part of flumen latum. The adjective latum directly describes flumen.

So flumen latum means:

• the wide river
• a wide river

not:

• the river flows widely

If Latin wanted to say widely, it would use an adverb, not the adjective latum.

Fluit is:

• 3rd person singular
• present tense
• active voice
• indicative mood

From the verb fluo, fluere = to flow

So fluit means:

• it flows

Since the subject is flumen (river), the sense is the river flows.

Because Classical Latin has no articles.

So flumen latum can mean:

• the wide river
• a wide river
• sometimes just wide river, depending on context

English requires an article in most cases, but Latin does not. The reader figures out whether the sense is the or a from context.

Flumen is a 3rd-declension neuter noun.

Its basic forms are:

• nominative singular: flumen
• genitive singular: fluminis

That genitive form, fluminis, is what tells you it belongs to the 3rd declension.

This is useful because many learners expect noun endings to work like 1st or 2nd declension nouns, but flumen follows different patterns.

Yes. Latin could also say latum flumen.

Both flumen latum and latum flumen are grammatically possible. Latin word order can shift for style, emphasis, rhythm, or clarity.

In a simple sentence like this, the meaning would stay the same. A beginner should focus mainly on the endings and agreement, not assume that adjective position works exactly like English.

Because of agreement.

• flumen is neuter singular
• latum is neuter singular
• urbem is feminine accusative singular

Since latum is neuter singular, it matches flumen, not urbem.

If the adjective were describing urbem, you would expect a feminine accusative singular form instead, such as latam.