Si via est longa, equus utilis est.

Si means if. It introduces a condition:

• Si via est longa = If the road is long
• equus utilis est = a horse is useful / the horse is useful

This is a simple, straightforward conditional statement, so Latin uses the normal indicative verb est.

Via is the subject of the first clause, so it is in the nominative case.

• via = nominative singular, road
• viam = accusative singular, used for a direct object

Since the sentence says the road is long, road is not being acted on; it is the thing being described. That is why Latin uses via.

Longa is an adjective describing via. In Latin, adjectives must agree with the nouns they describe in:

• gender
• number
• case

Via is:

• feminine
• singular
• nominative

So the adjective must also be feminine singular nominative: longa.

Equus is the subject of the second clause, so it is also in the nominative case.

• equus = nominative singular, horse
• equum = accusative singular, horse as a direct object

In equus utilis est, the horse is the thing being described as useful, so equus is nominative.

Utilis is a third-declension adjective. Its nominative singular forms are:

• masculine: utilis
• feminine: utilis
• neuter: utile

Since equus is masculine singular nominative, the correct form is utilis.

A learner might expect an adjective ending like -us, but not all Latin adjectives work that way. Utilis belongs to a different adjective pattern.

Because there are two separate clauses, and each one has its own verb:

• Si via est longa = If the road is long
• equus utilis est = a horse is useful

Each clause needs its own is verb. Latin can sometimes omit a form of esse (to be) if it is clearly understood, but in a basic sentence like this, keeping both est forms is normal and clear.

It can mean either one, depending on context.

Latin has no definite or indefinite article, so there is no separate word for the or a/an here.

So equus utilis est could be translated as:

• a horse is useful
• the horse is useful

The surrounding context would tell you which is more natural.

No. Latin word order is fairly flexible because the endings show the grammatical roles.

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

• Si via longa est, equus utilis est.
• Equus utilis est, si via est longa.
• Si longa via est, equus utilis est.

That said, some word orders sound more natural or more emphatic than others. The given version is simple and clear.

Because this is a simple real condition: If the road is long, a horse is useful.

Latin often uses the indicative in conditions that present something as a real or general possibility. So:

• si ... est
• ... est

A subjunctive would suggest a different kind of condition in certain contexts, but this sentence is just stating a basic fact or general rule.

A simple classroom pronunciation would be:

See WEE-ah est LONG-ah, EH-kwoos oo-TEE-lis est.

A few helpful notes:

• si sounds like see
• via is usually pronounced WEE-ah
• equus begins with e
  • qu, so roughly EH-kwoos
• c is always hard in Classical Latin, though there is no c in this sentence
• v in Classical pronunciation is like English w

If your course uses an ecclesiastical pronunciation, some sounds may differ slightly.