Mater dicit colonam non solum magnae industriae, sed etiam magnae patientiae esse.

Because this sentence uses indirect statement after dicit.

In Latin, after verbs like dicit (says), the subject of the reported statement goes into the accusative, and the verb goes into the infinitive.

So in:

Mater dicit colonam ... esse

the person being talked about inside the reported statement is colonam, so it is accusative.

In English we say:

• Mother says that the female farmer is ...

But Latin does not use that here. Instead it uses:

• [accusative subject] + [infinitive verb]

So colonam esse = that the female farmer is.

This is the accusative-and-infinitive construction, often called an indirect statement.

The pattern is:

• main verb of saying/thinking/perceiving
• accusative subject
• infinitive

Here:

• Mater = the subject of the main verb
• dicit = says
• colonam = accusative subject of the indirect statement
• esse = infinitive, to be

So literally the structure is:

• Mother says the female farmer to be ...

That sounds awkward in English, so we translate it as:

• Mother says that the female farmer is ...

Because Latin usually does not use a conjunction like English that after verbs of saying, thinking, knowing, hearing, and so on when reporting a statement.

English:

• Mother says that the female farmer is ...

Latin:

• Mater dicit colonam ... esse

The idea of that is built into the accusative + infinitive construction. So the indirect statement itself does the job that that does in English.

They are examples of the genitive of description/quality.

Latin can express a quality by saying someone is of some quality:

• magnae industriae = of great industry / diligence
• magnae patientiae = of great patience

So the sentence does not literally say the woman is great diligence or is great patience. Instead it says she is of great diligence and of great patience.

This is a very natural Latin way to describe a person’s character.

Because industriae is not a direct object here. It is part of a genitive phrase of quality.

Compare:

• magnam industriam habet = she has great diligence
  
  • here industriam is accusative because it is the object of habet

But in your sentence:

• est magnae industriae = she is of great diligence

Here the idea is descriptive, not an object. So Latin uses the genitive:

• industriae
• with agreeing adjective magnae

The same is true for magnae patientiae.

It is a very common paired expression meaning:

• not only ... but also

Here it links the two qualities:

• non solum magnae industriae
• sed etiam magnae patientiae

So the sense is:

• not only of great diligence, but also of great patience

Latin often uses this pair exactly where English would use not only ... but also.

It is repeated because each genitive phrase stands on its own:

• magnae industriae
• magnae patientiae

Each adjective agrees with its noun in:

• gender: feminine
• number: singular
• case: genitive

Latin often repeats an adjective in parallel phrases like this, especially for clarity and balance.

It would be much less neat if the adjective were not repeated, since the sentence is carefully balancing two qualities.

Esse is the infinitive of sum, meaning to be.

In the indirect statement, it is the verb that goes with colonam:

• colonam ... esse = that the female farmer is ...

Everything between colonam and esse tells us what kind of person she is.

So the core of the reported statement is:

• colonam esse

and then Latin adds the descriptive genitives:

• colonam magnae industriae esse
• colonam magnae patientiae esse

Because Latin word order is flexible, and infinitives—especially esse—often come at or near the end of the clause.

Placing esse at the end lets the sentence build up first:

• the reported subject: colonam
• the two qualities: non solum magnae industriae, sed etiam magnae patientiae
• then the verb: esse

This is a very normal Latin arrangement. English word order is much stricter, but Latin often saves the verb for the end.

No. Mater belongs to the main clause.

Main clause:

• Mater dicit = Mother says

Indirect statement:

• colonam non solum magnae industriae, sed etiam magnae patientiae esse

So mater is the one doing the saying, while colonam is the subject inside what is being said.

Yes. Grammatically, they mean:

• of great diligence
• of great patience

But idiomatic English might prefer something like:

• very hardworking
• very diligent
• very patient

So although the Latin uses noun phrases, English often switches to adjectives for smoother translation.

Still, for understanding the grammar, it is helpful to remember the more literal pattern:

• of great diligence
• of great patience