Αυτή η φάση τελειώνει αύριο.

In Greek, a demonstrative like this is normally used together with the definite article.

So Greek has:

• αυτή = this (feminine singular)
• η = the (feminine singular)
• φάση = phase

Together, αυτή η φάση literally looks like this the phase, but that is the normal Greek pattern.

Compare:

• αυτό το βιβλίο = this book
• αυτός ο άνθρωπος = this man
• αυτή η ιδέα = this idea

So the article is not extra here; it is part of the standard structure.

Because φάση is a feminine singular noun, and both the demonstrative and the article must agree with it in gender, number, and case.

Here:

• φάση is feminine
• it is singular
• it is the subject of the sentence, so it is in the nominative case

That is why you get:

• αυτή = feminine singular nominative
• η = feminine singular nominative article

If the noun were masculine or neuter, the forms would change:

• αυτός ο δρόμος = this road
• αυτό το μέρος = this place

There are two clues:

1. The article is η, which marks a feminine singular noun.
2. The noun ends in -η, which is a very common feminine ending in Greek.

That said, Greek noun gender is something you usually learn together with the noun. A good habit is to memorize nouns with their article:

• η φάση
• η μέρα
• η πόλη

That helps you remember both the gender and the basic nominative form.

τελειώνει is the 3rd person singular present tense form of the verb τελειώνω, meaning to end / to finish.

So:

• τελειώνω = I end / I finish
• τελειώνεις = you end
• τελειώνει = he/she/it ends

Since the subject αυτή η φάση is singular, the verb is singular too.

Because Greek, like English, can use the present tense for a future event when the context makes the time clear.

In English, you can say:

• The semester ends tomorrow
• The train leaves at six

Greek does the same thing:

• Αυτή η φάση τελειώνει αύριο.

This often sounds natural when talking about something scheduled, expected, or already arranged.

So even though τελειώνει is grammatically present, the sentence refers to the future because of αύριο.

Yes, that is also correct.

• Αυτή η φάση τελειώνει αύριο = natural present used for a future event
• Αυτή η φάση θα τελειώσει αύριο = explicit future with θα

Both can mean basically the same thing in many contexts.

A rough nuance is:

• τελειώνει αύριο can sound a bit like it ends tomorrow
• θα τελειώσει αύριο can sound a bit more like it will end tomorrow

The difference is often small, and context matters.

It can mean either, depending on context.

Greek does not separate the simple present and the progressive present as strictly as English does. So τελειώνει can correspond to:

• ends
• is ending
• sometimes even finishes

In this sentence, because of αύριο, the natural English translation is ends tomorrow, not is ending tomorrow.

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

The neutral order here is:

• Αυτή η φάση τελειώνει αύριο.

But you could also say:

• Αύριο τελειώνει αυτή η φάση.

That puts more emphasis on tomorrow.

You may also hear other variations in speech, depending on what the speaker wants to stress. Greek uses word order partly for emphasis, not only for grammar.

Often yes, especially in more literal or formal contexts. It can mean:

• a phase
• a stage
• a period in a process

But in everyday Greek, φάση is also very common in broader, more colloquial meanings, such as:

• a situation
• a vibe
• a whole thing someone is going through

So depending on context, αυτή η φάση could mean something like:

• this phase
• this stage
• this situation

In your sentence, the meaning is probably the straightforward phase/stage sense.

A simple pronunciation guide is:

af-TI i FA-si te-li-O-ni AV-rio

A few helpful notes:

• αυ before the voiceless consonant τ is pronounced like af
• η is pronounced i
• φ sounds like f
• τελειώνει has the stress on -ώ-
• αύριο is stressed on the first syllable

So the whole sentence is approximately:

af-TI i FA-si te-li-O-ni AV-rio

It is in the nominative case, because it is the subject of the sentence.

In other words, this phase is the thing that ends.

That is why you see the nominative forms:

• αυτή
• η
• φάση

If the phrase were used in another role in the sentence, some forms could change, especially the demonstrative and article.