Αυτό είναι το φυτό εσωτερικού χώρου.

Here Αυτό means this.

In Greek, αυτός / αυτή / αυτό can mean this or he/she/it, depending on context. In this sentence, Αυτό είναι... is the very common pattern for This is...

Because φυτό is a neuter noun, the form used is αυτό.

• masculine: αυτός
• feminine: αυτή
• neuter: αυτό

So Αυτό είναι το φυτό... = This is the plant...

Είναι means is or are.

It is the 3rd person singular/plural form of the verb είμαι = to be.

So:

• είναι = is
• but also είναι = are, depending on the subject

In your sentence:

• Αυτό είναι... = This is...

Greek does not change this form between is and are.

Το is the definite article here, meaning the.

So:

• το φυτό = the plant

Greek uses articles very often, sometimes more often than English. Since the sentence is talking about a specific item, Greek naturally uses το.

Also, το matches the gender and number of φυτό, which is:

• neuter
• singular

That is why it is το φυτό, not ο φυτό or η φυτό.

Φυτό is a neuter noun.

Yes, that matters, because in Greek the article and some related words must agree with the noun’s gender, number, and case.

That is why you see:

• αυτό = neuter
• το = neuter
• φυτό = neuter noun

So the sentence is internally matching correctly.

Literally, εσωτερικού χώρου means something like of interior space or for indoor space.

It is a very common Greek way to express what English often says with a single adjective like indoor.

So:

• φυτό εσωτερικού χώρου = indoor plant / houseplant

Word by word:

• εσωτερικού = interior / indoor in the genitive
• χώρου = space / room / area in the genitive

Together they form a phrase describing the kind of plant.

They are both in the genitive singular.

This is a common Greek structure. Greek often uses the genitive where English would use an adjective or a noun-noun combination.

Here the phrase works like a label:

• φυτό εσωτερικού χώρου = plant of indoor space → more naturally, indoor plant

The base forms are:

• εσωτερικός = interior / indoor
• χώρος = space, room, area

In the phrase, they become:

• εσωτερικού
• χώρου

because Greek is building a genitive expression.

It is understandable, but it usually does not mean exactly the same thing.

• φυτό εσωτερικού χώρου is the natural way to say indoor plant / houseplant
• εσωτερικό φυτό sounds more like an internal plant or just a more literal adjective use, which is less idiomatic in this context

So if you mean a plant kept inside a home or building, φυτό εσωτερικού χώρου is the better choice.

Grammatically, because of το, it is literally This is the indoor plant.

However, article use does not always line up perfectly between Greek and English. Depending on context, English might sometimes translate it more naturally as:

• This is the indoor plant
• This is an indoor plant
• This is the houseplant

If you are just learning the structure, the important thing is that Greek uses το φυτό here as a normal definite noun phrase.

A simple pronunciation guide would be:

af-TO EE-ne to fee-TO e-so-te-ri-KOO HO-roo

A few helpful notes:

• Αυτό sounds like af-TO
• είναι sounds like EE-ne
• φ is like English f
• χ in χώρου is a rough sound, not exactly like English h, but HO-roo is a useful approximation for beginners

So the full sentence is:

Αυτό είναι το φυτό εσωτερικού χώρου.
af-TO EE-ne to fee-TO e-so-te-ri-KOO HO-roo

Yes, Greek word order is more flexible than English, but this version is the most straightforward.

• Αυτό είναι το φυτό εσωτερικού χώρου. = This is the indoor plant.

If you changed the order, the meaning might still be understandable, but the emphasis would shift. For a basic identifying sentence, the given order is the most natural and beginner-friendly.

So this pattern is a good one to remember:

Αυτό είναι + noun phrase = This is + noun phrase