Colona quae praedio praeest magnae industriae est.

The sentence has:

• a main clause: Colona ... magnae industriae est
• a relative clause inside it: quae praedio praeest

So the skeleton is:

• Colona est = the woman/female farmer is
• quae praedio praeest = who is in charge of the estate
• magnae industriae = of great industry / very industrious

Latin often places a relative clause right after the noun it describes, just as English does.

Quae is a relative pronoun, meaning who here.

It refers back to colona, so it is:

• feminine because colona is feminine
• singular because colona is singular

Its case is nominative, not because colona is nominative, but because quae is the subject of praeest inside its own clause.

A very important rule:

• a relative pronoun agrees with its antecedent in gender and number
• but its case depends on its job in the relative clause

So here:

• colona = feminine singular
• quae = feminine singular nominative, because she is the one who is in charge

Because praeest comes from praeesse, and praeesse takes the dative.

So:

• praedio praeest = she is in charge of the estate
• literally something like she is over the estate

This is one of those verbs whose construction has to be learned. English says be in charge of, but Latin uses praeesse + dative.

Also, a learner often notices that praedio could look like either dative or ablative singular. Here it is dative, because the verb requires that case.

Praeest is the 3rd person singular present indicative active of praesum, praeesse.

It is a compound of:

• prae- = before, in front of, over
• sum, esse = to be

So praeesse literally means to be over, and in normal English that becomes:

• to be in charge of
• to preside over
• to supervise

That is why praeest can be translated naturally as is in charge of.

Because they belong to two different clauses.

• praeest is the verb of the relative clause: quae praedio praeest
• est is the verb of the main clause: colona ... magnae industriae est

Even though praeest is historically built from sum, it functions as its own separate verb meaning is in charge of.

So this is not repetition by mistake. It is simply:

• who is in charge ...
• is of great industry

Magnae industriae est uses the genitive of quality (also called the genitive of description).

So:

• magnae = genitive singular feminine of magnus
• industriae = genitive singular of industria

Together they mean:

• of great industry
• more naturally in English, very industrious

This is a common Latin way to describe a person’s quality or character.

So:

• magnae industriae est = she is of great industry
• idiomatic English: she is very industrious

If Latin wanted a simple predicate adjective, it might instead use an adjective such as industriosa.

Because colona is nominative singular, and the main verb est is 3rd person singular.

So the main clause is:

• Colona ... est = The woman/female farmer ... is

The relative clause quae praedio praeest just adds information about that subject.

A helpful way to see it is:

• Colona est
• Which colona?
• quae praedio praeest

Because classical Latin has no definite or indefinite articles.

So Latin does not normally have separate words for:

• the
• a
• an

Whether you translate colona as the female farmer, a female farmer, or just female farmer depends on context.

English needs an article; Latin usually does not.

It is not unusual for Latin.

Latin word order is much more flexible than English word order because the endings show grammatical relationships. Here the order is quite natural:

• Colona — the noun being talked about
• quae praedio praeest — the relative clause describing her
• magnae industriae est — the statement about her quality

English depends heavily on word order, but Latin can move pieces around for emphasis, rhythm, or style.

So even though the sentence may feel less direct to an English speaker, its order is perfectly normal Latin.

Grammatically, quae is just the feminine singular relative pronoun. English chooses who or which based on meaning.

Since colona is a person, English normally says who:

• the woman who is in charge of the estate

If the antecedent were a thing, English would more naturally use which.

So the Latin form itself does not separately mark who versus which the way English does; context tells you which English word is appropriate.