Mox puer fortis erit, et miles erit.

Erit is the future tense of esse (to be), in the third person singular: he/she/it will be.

So:

• est = is
• erit = will be

Because the sentence is talking about what the boy will be, Latin uses erit.

Yes, Latin could leave it out. A sentence like Mox puer fortis erit, et miles could still be understood as Soon the boy will be brave, and a soldier.

But repeating erit is perfectly normal and often clearer. It gives the sentence a balanced structure:

• puer fortis erit
• et miles erit

So the repetition is not wrong or strange; it is just explicit and neat.

Latin word order is much freer than English word order because endings carry a lot of grammatical information.

Both puer fortis and fortis puer can mean a brave boy or the brave boy, depending on context. In this sentence, puer fortis is simply a natural way to put the noun and adjective together.

Sometimes word order gives emphasis, but here the basic meaning does not change.

We know because fortis is an adjective and it agrees with puer in:

• gender: masculine
• number: singular
• case: nominative

Puer is nominative singular masculine, and fortis is also nominative singular masculine/feminine in form. That tells us fortis describes puer.

Because fortis belongs to the third-declension adjective pattern, not the first/second-declension adjective pattern.

Some adjectives work like:

• bonus, bona, bonum

But fortis works like:

• masculine/feminine nominative singular: fortis
• neuter nominative singular: forte

So with puer, the correct form is fortis.

Both puer and miles are in the nominative singular.

That is because they are used with forms of esse (to be):

• puer fortis erit = the boy will be brave
• miles erit = he will be a soldier

After to be, Latin commonly uses the nominative for the predicate noun as well. So miles is nominative, not accusative.

Latin does not have definite or indefinite articles like English the and a/an.

So:

• puer can mean boy, a boy, or the boy
• miles can mean soldier, a soldier, or the soldier

Context tells you which is most natural in translation.

Not really. The understood subject is still puer.

The sentence works like this:

• Mox puer fortis erit
• et [puer] miles erit

In the second part, puer is not repeated because it is already understood. Miles is a predicate noun, telling us what the boy will be.

Et means and. It joins the two ideas:

• the boy will be brave
• the boy will be a soldier

It is a very common coordinating conjunction.

Yes. That would still be grammatical Latin.

Because Latin word order is flexible, forms like these are possible:

• Mox puer fortis erit, et miles erit
• Mox puer erit fortis, et miles erit
• Mox puer fortis erit et miles erit

The exact order can affect emphasis or style, but the basic meaning remains the same.

Grammatically, miles is a masculine noun in Latin. In many classical contexts it usually refers to a male soldier.

For this sentence, the grammar is straightforward because the subject puer is also masculine. So miles fits naturally.

They are:

• mox = soon
• puer, pueri = boy
• fortis, forte = brave
• sum, esse, fui, futurus = to be
• miles, militis = soldier

Knowing the dictionary form helps you recognize how the words are functioning in the sentence.

Because miles is a third-declension noun. Third-declension nominative singular forms are often less predictable than first- or second-declension ones.

Its forms include:

• nominative singular: miles
• genitive singular: militis

The genitive militis is what shows you the stem milit-.

Yes. Latin can use esse with:

• a predicate adjective: puer fortis erit
• a predicate noun: miles erit

This sentence has both, one after the other. First it says what the boy will be like (fortis), then what he will be (miles). That makes it a useful example of two common patterns with esse.