Το ενυδρείο είναι πάνω στο γραφείο και έχει δύο μικρά ψάρια.

το is the definite article for a neuter singular noun, so it means the.

• το ενυδρείο = the aquarium
• ενυδρείο is a neuter noun
• In dictionary form, it appears as το ενυδρείο

Greek uses the definite article very often, much like English uses the, but in Greek the article also shows the noun’s gender, number, and case.

ενυδρείο means aquarium or fish tank.

It is:

• neuter
• singular
• here it is in the nominative case, because it is the subject of the sentence

So:

• Το ενυδρείο είναι... = The aquarium is...

Many Greek neuter nouns end in -ο or -ι, but ενυδρείο ends in -είο, which is also a common neuter pattern.

είναι is the modern Greek form of is / are from the verb είμαι = to be.

In this sentence:

• Το ενυδρείο είναι πάνω στο γραφείο = The aquarium is on the desk

A few useful forms of είμαι:

• είμαι = I am
• είσαι = you are
• είναι = he/she/it is, or they are

So είναι is exactly the correct form here because the subject is it: the aquarium.

πάνω στο γραφείο means on the desk or on top of the desk.

Breakdown:

• πάνω = up / above / on top
• στο = σε + το = in/on/to the
• γραφείο = desk

So literally it is something like:

• above/on the desk

In natural English, this becomes:

• on the desk

Greek often uses πάνω σε or πάνω σε + article to express on.

στο is the normal contracted form of σε το.

So:

• σε + το = στο
• σε + τη = στη(ν)
• σε + τον = στον

This is extremely common in Greek.

Examples:

• στο γραφείο = on/in/to the desk
• στην πόλη = in the city
• στο σπίτι = at home / in the house

So πάνω στο γραφείο is just the natural way to say on the desk.

It is in the accusative case.

The preposition σε normally takes the accusative, so:

• στο γραφείο = σε το γραφείο
• γραφείο here is accusative singular

Because γραφείο is a neuter noun, the nominative and accusative forms are often the same in appearance, so you do not see a change in the noun itself.

Compare:

• το γραφείο = the desk
• βλέπω το γραφείο = I see the desk
• στο γραφείο = on/in/to the desk

Same form, different grammatical function.

και means and.

It joins the two parts of the sentence:

• Το ενυδρείο είναι πάνω στο γραφείο
• και έχει δύο μικρά ψάρια

So the full structure is:

• The aquarium is on the desk and has two small fish

It is a very common coordinating conjunction, just like English and.

Greek often drops subject pronouns when they are not needed, because the verb ending already gives enough information.

Here:

• έχει = it has / he has / she has

Since the subject το ενυδρείο was already mentioned, Greek does not need to repeat it.

So:

• Το ενυδρείο ... έχει δύο μικρά ψάρια literally:
• The aquarium ... has two small fish

Greek does this all the time:

• Έχω = I have
• Έχεις = you have
• Έχει = he/she/it has

A separate pronoun is usually only added for emphasis or contrast.

Because the sentence means two small fish, so the noun phrase must be plural.

Breakdown:

• δύο = two
• μικρά = small plural neuter
• ψάρια = fish plural neuter

The noun ψάρι means fish in the singular. Its plural is ψάρια.

So:

• ένα μικρό ψάρι = one small fish
• δύο μικρά ψάρια = two small fish

The adjective must agree with the noun, so:

• singular neuter: μικρό
• plural neuter: μικρά

Usually, no. δύο is generally indeclinable in modern Greek, meaning it stays the same.

So you can use δύο with different nouns without changing it:

• δύο βιβλία = two books
• δύο παιδιά = two children
• δύο μικρά ψάρια = two small fish

The words around it may change for gender, number, and case, but δύο normally does not.

In Greek, adjectives often come before the noun, just as in English.

So:

• μικρά ψάρια = small fish

The adjective μικρά agrees with ψάρια in:

• gender: neuter
• number: plural
• case: accusative here

Because ψάρια is neuter plural, the adjective must also be neuter plural:

• μικρά

This is a very important Greek pattern: adjectives match the nouns they describe.

ψάρια is in the accusative plural.

It is the direct object of έχει:

• has what? → two small fish

So:

• έχει δύο μικρά ψάρια = it has two small fish

Since ψάρι is a neuter noun, the plural nominative and accusative are the same form:

• ψάρια

That is why it looks the same whether it is a subject or an object.

Yes. Greek word order is more flexible than English word order, although the version you have is very natural.

Your sentence:

• Το ενυδρείο είναι πάνω στο γραφείο και έχει δύο μικρά ψάρια.

This is the most straightforward neutral order.

You might also hear variations for emphasis, such as:

• Πάνω στο γραφείο είναι το ενυδρείο... if someone wants to emphasize where it is
• Το ενυδρείο έχει δύο μικρά ψάρια και είναι πάνω στο γραφείο. if the speaker changes the focus

But for a learner, the given sentence is an excellent standard model.

A simple pronunciation guide is:

To en-nee-thREE-o EE-ne pan-o sto gra-FEE-o ke E-chee THEE-o mee-KRA PSA-ria

A few useful notes:

• αι sounds like e
• ει sounds like ee
• οι also sounds like ee
• χ in έχει is not like English h; it is a softer throat sound
• ψ in ψάρια is pronounced like ps together, as in lapse

The stressed syllables are:

• ενυδρείο
• είναι
• γραφείο
• έχει
• μικρά
• ψάρια