Την Πρωτοχρονιά πηγαίνουμε στην εκκλησία το πρωί και μετά πίνουμε καφέ μαζί.

Because here Πρωτοχρονιά is being used as a time expression, meaning on New Year’s Day. In Greek, many expressions of when something happens use the accusative case.

So:

• η Πρωτοχρονιά = New Year’s Day as the subject
• την Πρωτοχρονιά = on New Year’s Day

The article changes too:

• nominative: η
• accusative: την

So Την Πρωτοχρονιά πηγαίνουμε... literally works like On New Year’s Day we go...

Πρωτοχρονιά means New Year’s Day, not New Year’s Eve.

It comes from:

• πρώτο- = first
• χρονιά = year

In everyday Greek, η Πρωτοχρονιά commonly refers to January 1st, the first day of the year. So this sentence is talking about a New Year’s Day custom or habit.

Greek often uses the present tense to talk about:

• habits
• routines
• customs
• things that generally happen

So πηγαίνουμε means we go, but in this sentence it has the sense of:

• we go (as a custom)
• we usually go
• we go on New Year’s Day

This is very natural in Greek. English often does the same:

• On Christmas we visit family.
• On New Year’s Day we go to church.

So the Greek present here is a habitual present.

Greek often does not need a separate subject pronoun because the verb ending already shows who is doing the action.

Here:

• πηγαίνουμε = we go
• πίνουμε = we drink / we have

The ending -ουμε tells you it is first person plural: we.

If you added εμείς (we), it would usually be for emphasis:

• Εμείς πηγαίνουμε... = We are the ones who go...

But in a normal sentence, Greek usually leaves we out.

στην is a contraction of:

• σε = to / in / at
• την = the

So:

• σε την εκκλησία → στην εκκλησία

This means to church or literally to the church.

Also, σε takes the accusative, which is why you get την εκκλησία.

A very important point for English speakers: Greek often uses the article where English does not. So although English says go to church, Greek naturally says πηγαίνουμε στην εκκλησία.

That is just a normal difference between the two languages.

In Greek, the article is used much more often than in English. So Greek says:

• πάω στην εκκλησία = I go to church
• literally: I go to the church

But in meaning, it is often just the normal idea of attending church, not necessarily emphasizing a specific building.

So do not translate the article too mechanically. In many cases, στην εκκλησία is simply the natural Greek way to say to church.

το πρωί means in the morning.

This is a fixed time expression in Greek. Many time phrases use the neuter article + noun/adverbial expression, for example:

• το πρωί = in the morning
• το βράδυ = in the evening / at night
• το μεσημέρι = at noon / at lunchtime

So in the sentence:

• πηγαίνουμε στην εκκλησία το πρωί = we go to church in the morning

You should learn το πρωί as a common chunk.

Here μετά means afterwards, then, or after that.

So:

• και μετά πίνουμε καφέ μαζί = and then we have coffee together

Important distinction:

• μετά on its own = afterwards / then
• μετά από + noun = after + noun

Examples:

• Μετά φεύγουμε. = Afterwards we leave.
• Μετά από μία ώρα φεύγουμε. = We leave after an hour.

In your sentence, μετά is being used by itself as an adverb.

Because Greek often leaves out the article with general, indefinite, or substance/activity nouns.

So:

• πίνουμε καφέ = we drink/have coffee
• literally, it is more like we drink coffee

This is the normal way to talk about the activity in general.

If you used an article, it would usually sound more specific:

• πίνουμε τον καφέ = we drink the coffee / we have our coffee
• πίνουμε έναν καφέ = we have a coffee / one coffee

So πίνουμε καφέ is the natural general expression here.

It can mean both, depending on context.

Literally, πίνουμε means we drink. But in natural English, this sentence is often better translated as:

• we have coffee together

That sounds more natural because it refers not just to the physical act of drinking, but also to the social activity.

So:

• πίνουμε καφέ μαζί = we drink coffee together
• very natural English: we have coffee together

μαζί means together.

Here it modifies the second action:

• πίνουμε καφέ μαζί = we have coffee together

Its position is quite natural at the end, but Greek word order is flexible. You may also hear:

• μαζί πίνουμε καφέ
• πίνουμε μαζί καφέ

Still, πίνουμε καφέ μαζί is a very normal and natural order.

No, Greek word order is fairly flexible. The sentence as written is natural, but other orders are possible depending on emphasis.

The given sentence:

• Την Πρωτοχρονιά πηγαίνουμε στην εκκλησία το πρωί και μετά πίνουμε καφέ μαζί.

Possible variations:

• Το πρωί την Πρωτοχρονιά πηγαίνουμε στην εκκλησία...
• Την Πρωτοχρονιά το πρωί πηγαίνουμε στην εκκλησία...

The main meaning does not change much, but the focus can shift slightly.

As written, the sentence flows very naturally:

1. time: Την Πρωτοχρονιά
2. action: πηγαίνουμε στην εκκλησία
3. time detail: το πρωί
4. next action: και μετά πίνουμε καφέ μαζί

It most naturally sounds like a tradition, custom, or usual family practice.

Because of the present tense (πηγαίνουμε, πίνουμε) and the time phrase Την Πρωτοχρονιά, the sentence suggests:

• This is what we do on New Year’s Day
• This is our New Year’s Day routine

If you wanted to describe a single future event, Greek would more likely use a future form, for example:

• Την Πρωτοχρονιά θα πάμε στην εκκλησία... = On New Year’s Day we will go to church...

So the original sentence most naturally describes a repeated custom.