Στο εστιατόριο η ατμόσφαιρα είναι πολύ ήσυχη απόψε.

Στο is the contracted form of σε + το.

So:

• σε = in / at / to
• το = the for a neuter noun
• στο = in the / at the / to the

In this sentence, στο εστιατόριο means in the restaurant.

This contraction is completely normal in Modern Greek and is usually what you should expect to see:

• σε + το → στο
• σε + τη(ν) → στη(ν)
• σε + τα → στα

After σε, Greek normally uses the accusative case.

So in full form, this is:

• σε το εστιατόριο

The noun εστιατόριο is neuter singular, and for many neuter nouns, the nominative and accusative forms are the same. So even though it is accusative here, it still looks like εστιατόριο.

That is why nothing seems to change on the noun itself.

Greek uses the definite article very often, and much more regularly than English.

Here, η ατμόσφαιρα means the atmosphere and functions as the subject of the sentence. In a sentence like this, using the article sounds natural and expected in Greek.

So:

• η = the for a feminine singular noun
• ατμόσφαιρα = atmosphere

Together: η ατμόσφαιρα = the atmosphere

Leaving out the article here would usually sound unnatural.

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

The noun ατμόσφαιρα is:

• feminine
• singular
• nominative here

So the adjective must also be feminine singular nominative:

• masculine: ήσυχος
• feminine: ήσυχη
• neuter: ήσυχο

Since the sentence says η ατμόσφαιρα, the correct form is ήσυχη.

This is a very common learner question.

Here, πολύ means very, so it is being used as an adverb, modifying the adjective ήσυχη.

• πολύ ήσυχη = very quiet

When πολύ means very, it stays πολύ.

By contrast, πολλή is the feminine form of the adjective meaning much / a lot of:

• πολλή ζάχαρη = a lot of sugar
• πολλή φασαρία = a lot of noise

So in this sentence, πολύ is correct because it means very, not much.

Απόψε means tonight and is very common in everyday Greek.

It is an adverb of time, so it does not need an article. It simply tells you when the situation is true.

You could also hear:

• σήμερα το βράδυ = this evening / tonight

But απόψε is shorter and very natural.

So:

• απόψε = tonight

Yes, Greek word order is more flexible than English word order.

This sentence begins with Στο εστιατόριο to set the scene first: In the restaurant...

That makes the location the starting point or topic of the sentence.

Other word orders are also possible, for example:

• Η ατμόσφαιρα στο εστιατόριο είναι πολύ ήσυχη απόψε.
• Απόψε η ατμόσφαιρα στο εστιατόριο είναι πολύ ήσυχη.

These versions are still grammatical, but the emphasis changes slightly.

So the original order is natural and puts focus first on where.

Yes. Είναι is the present-tense form of to be: is / are.

In this sentence, it links the subject η ατμόσφαιρα with the description πολύ ήσυχη.

So:

• η ατμόσφαιρα = subject
• είναι = is
• πολύ ήσυχη = description

Unlike some languages that may omit is in this kind of sentence, Greek normally keeps it:

• η ατμόσφαιρα είναι ήσυχη = the atmosphere is quiet

It can suggest both, depending on context.

With ατμόσφαιρα, ήσυχη can mean:

• quiet in the sense of not noisy
• calm
• peaceful
• relaxed

So it is a good word for describing the ambience of a place, not just sound level in a narrow sense.

That is why it fits naturally with ατμόσφαιρα.

A rough pronunciation guide:

• Στο → sto
• εστιατόριο → e-stya-TO-rio
• η ατμόσφαιρα → ee at-MO-sfe-ra
• είναι → EE-ne
• πολύ → po-LEE
• ήσυχη → EE-si-khi
• απόψε → a-PO-pse

A few helpful notes:

• The accent mark shows the stressed syllable.
• η is pronounced like ee.
• ει in είναι is also pronounced ee in Modern Greek.
• χ in ήσυχη is not an English k sound; it is a rougher sound, like German ch in ich or a soft breathy h-like sound.

It sounds natural.

A Greek speaker would easily say something like this to describe the ambience of a place. The sentence is clear, idiomatic, and grammatically normal.

It has a very natural structure:

• location first: Στο εστιατόριο
• subject: η ατμόσφαιρα
• verb: είναι
• description: πολύ ήσυχη
• time: απόψε

So this is a good model sentence for learners.