Ex monte ad vallem aqua currit.

Because ex takes the ablative case, and the ablative singular of mons (mountain) is monte.

So:

• mons = mountain as a dictionary form / nominative
• monte = from the mountain after ex

This is a very common Latin pattern: a preposition often tells you what case the following noun must be in.

Because ad takes the accusative case, and the accusative singular of vallis (valley) is vallem.

So:

• vallis = dictionary form / nominative
• vallem = to/toward the valley after ad

In this sentence, ad vallem shows motion toward a place.

In this sentence:

• ex
  • ablative = out of / from
• ad
  • accusative = to / toward

So:

• ex monte = from the mountain
• ad vallem = to the valley

These are standard pairings that learners should memorize early, because Latin relies heavily on case endings after prepositions.

Because aqua is the subject of currit.

The verb currit means runs or, in this context, flows. The thing doing that action is water, so aqua is nominative singular.

Structure:

• aqua = the water
• currit = flows / runs

Even though English often puts the subject first, Latin does not have to. The nominative ending helps show that aqua is the subject.

Because Latin often uses currere broadly for movement, including the movement of water.

So although the basic meaning is to run, in a sentence about water, English usually translates it more naturally as flows.

This is common in language learning: the most literal meaning of a word is not always the best translation in context.

Latin word order is much more flexible than English word order because the case endings show each word’s role.

So all of these could express roughly the same basic idea:

• Ex monte ad vallem aqua currit.
• Aqua ex monte ad vallem currit.
• Ex monte aqua ad vallem currit.

The chosen order can affect emphasis or style, but the endings still tell you:

• aqua = subject
• monte = ablative after ex
• vallem = accusative after ad

English depends much more on word order to show meaning.

Yes, depending on context.

Strictly speaking, ex means out of / from, so ex monte is literally from the mountain. But since water naturally moves downward, an English translation like down from the mountain may sound more natural.

Still, the Latin itself does not explicitly say down. That idea comes from the real-world situation, not from a separate Latin word here.

Because Latin has no definite article like English the and no indefinite article like a/an.

So:

• mons can mean mountain or the mountain
• vallis can mean valley or the valley
• aqua can mean water or the water

You decide from context which English article sounds best.

Not normally.

Both ex and ab can be translated as from, but they are used differently.

• ex often means out of, from within, or from
• ab often means away from or from the vicinity of

With a mountain, ex monte is the natural choice in a sentence like this. It gives the sense of water coming from the mountain. Ab monte is less natural here.

The sentence gives you examples from different declensions:

• mons, montis = 3rd declension
• vallis, vallis = 3rd declension
• aqua, aquae = 1st declension

Their forms here are:

• monte = ablative singular of mons
• vallem = accusative singular of vallis
• aqua = nominative singular of aqua

So this one short sentence already shows how important it is to recognize noun endings rather than rely only on position in the sentence.

A common classroom pronunciation would be roughly:

eks MON-teh ad WAL-lem AH-kwah KOOR-rit

A few helpful points:

• ex sounds like eks
• v in restored classical pronunciation sounds like English w, so vallem is closer to wallem
• qu is pronounced like kw, so aqua is akwa
• c in Latin is always hard, so currit begins like koor-

Exact pronunciation depends on whether you are using a classical or ecclesiastical system, but the grammar of the sentence stays the same.