In hac historia una persona prudentissima est, altera autem minus prudens.

Because in here means in in the sense of location, so it takes the ablative case.

• haec historia = nominative, this story
• hac historia = ablative, in this story

So in hac historia means in this story. If in meant motion into, it would take the accusative instead.

It is nominative singular. It is the subject of the sentence: one person.

The adjective una agrees with persona in:

• gender: feminine
• number: singular
• case: nominative

So una persona prudentissima est means one person is very / most prudent.

This is a very common Latin pattern:

• una = one
• altera = the other

Together, una ... altera means one ... the other. Latin often uses alter for the other of two, so this wording strongly suggests a contrast between two people.

Because it refers back to persona, which is a feminine noun.

Even though the noun is not repeated, Latin still makes the word agreeing with it feminine:

• una persona
• altera = the other one / the other person

So altera is feminine singular nominative because the understood noun is persona.

Because Latin often leaves out a noun when it is already obvious from the context.

So altera autem minus prudens really means: altera persona autem minus prudens

English does this too sometimes, as in one person is wise; the other less so. Latin just does it very naturally.

autem usually means however, but, or on the other hand.

It is a postpositive word, which means it normally comes after the first word or phrase of its clause, not before it. So Latin prefers:

• altera autem

  rather than

• autem altera

That word order is normal and idiomatic.

Prudentissima is the superlative form of prudens.

The basic pattern is:

• prudens = prudent, wise
• prudentior = more prudent
• prudentissimus / prudentissima / prudentissimum = most prudent, very prudent

Here it is prudentissima because it agrees with persona, which is feminine singular.

Because prudens is a third-declension adjective whose nominative singular form is the same for masculine and feminine.

So:

• masculine singular nominative: prudens
• feminine singular nominative: prudens

That is why it does not change to something like prudenta. Latin adjectives do not all follow first/second-declension patterns.

Minus means less, so minus prudens means less prudent.

This is a normal Latin way to make a comparison in the direction of less:

• doctus = learned
• minus doctus = less learned

So altera autem minus prudens means the other, however, is less prudent.

Yes, an est is understood.

The full version would be: In hac historia una persona prudentissima est, altera autem minus prudens est.

Latin often omits forms of esse when they are easy to supply from the context, especially in parallel sentences like this one.

It can mean either, depending on context.

Latin superlatives often have two possible senses:

• relative superlative: most prudent
• absolute superlative: very prudent or extremely prudent

In a sentence like this, either may be possible, but the main idea is a strong contrast: one person is at a very high level of prudence, while the other is less prudent.

Not necessarily.

The words are feminine because they agree with persona, and persona is grammatically feminine. In Latin, grammatical gender and biological sex are not always the same thing.

So the sentence’s grammar does not by itself prove that the people are women; it only shows that the noun being used is feminine.