Αυτή η πολιτεία είναι μεγάλη.

A simple breakdown is:

• Αυτή = this
• η = the
• πολιτεία = state, city, or another context-dependent meaning of polity/commonwealth
• είναι = is
• μεγάλη = big or large

So grammatically:

• Αυτή η πολιτεία is the subject, meaning this state
• είναι is the verb, meaning is
• μεγάλη is a predicate adjective, describing the subject: big/large

Yes, αυτή already means this, but in Modern Greek it is normal to use the demonstrative together with the definite article before a noun:

• αυτή η πολιτεία = this state

This is the standard pattern in Greek. English says this state, but Greek usually says literally something like this the state.

So Αυτή πολιτεία would sound incomplete or ungrammatical in standard Modern Greek.

Because πολιτεία is feminine singular, and the demonstrative has to agree with it.

The basic forms are:

• αυτός = masculine
• αυτή = feminine
• αυτό = neuter

Since πολιτεία is feminine, Greek uses the feminine form:

• αυτή η πολιτεία

If the noun were neuter, you would use αυτό. If it were masculine, you would use αυτός.

There are two clues here:

1. The article is η, which is the feminine singular nominative article.
2. The adjective and demonstrative also appear in feminine forms: αυτή and μεγάλη.

Also, nouns ending in -ία are very often feminine in Greek, though you should still learn nouns with their article when possible:

• η πολιτεία

That is a very useful habit in Greek, because the article helps you remember the noun’s gender.

Because adjectives in Greek agree with the noun they describe in gender, number, and case.

Here:

• πολιτεία is feminine
• singular
• nominative

So the adjective must match it:

• masculine: μεγάλος
• feminine: μεγάλη
• neuter: μεγάλο

Since the noun is η πολιτεία, the correct form is μεγάλη.

Αυτή η πολιτεία is in the nominative case because it is the subject of the sentence.

The adjective μεγάλη is also nominative feminine singular because it is a predicate adjective linked to the subject by είναι.

So even though μεγάλη comes after the verb, it still matches the subject:

• subject: Αυτή η πολιτεία
• predicate adjective: μεγάλη

This is similar to English This state is big, where big describes the subject.

Πολιτεία can have several meanings depending on context. Common possibilities include:

• state
• commonwealth
• government
• sometimes city in certain contexts
• more abstract senses related to system of government or polity

So you should not assume it always means just one thing. The surrounding context tells you which English translation fits best.

In this sentence, if the meaning shown to the learner is something like This state is big, then πολιτεία is being used in that sense.

A rough pronunciation guide is:

af-TEE ee po-lee-TEE-a EE-ne ME-ga-lee

A few useful notes:

• αυτή is stressed on the last syllable
• πολιτεία is stressed on -τεί-
• είναι is stressed on the first syllable
• μεγάλη is stressed on γά

Also, η is pronounced ee, the same sound as ι in Modern Greek.

The accent mark in Modern Greek shows which syllable is stressed.

So:

• αυτή has stress on the last syllable
• πολιτεία has stress on -τεί-
• είναι has stress on the first syllable
• μεγάλη has stress on γά

But η is a one-syllable article, and ordinary monosyllabic words usually do not take a written accent mark.

So η has no accent, even though it is pronounced.

Είναι can mean both is and are in the present tense.

For example:

• Η πολιτεία είναι μεγάλη = The state is big
• Οι πολιτείες είναι μεγάλες = The states are big

So είναι does not change between third person singular and third person plural. The subject tells you whether it means is or are.

Greek word order is more flexible than English, because the endings and articles show grammatical relationships more clearly.

The neutral, straightforward order here is:

• Αυτή η πολιτεία είναι μεγάλη

But Greek can move things for emphasis. For example, a different order could emphasize μεγάλη.

Still, for learners, the safest and most natural basic pattern is:

• demonstrative + article + noun + είναι + adjective

So this sentence is a very good model to follow.