Η ημερομηνία λήξης είναι αύριο.

Word by word:

• Η = the (feminine singular)
• ημερομηνία = date
• λήξης = of expiry / expiration
• είναι = is
• αύριο = tomorrow

So η ημερομηνία λήξης literally means the date of expiry, which is the natural Greek way to say the expiration date / expiry date.

Greek nouns have grammatical gender. ημερομηνία is a feminine noun, so it takes the feminine singular definite article:

• ο = masculine the
• η = feminine the
• το = neuter the

Because ημερομηνία is feminine, you say:

• η ημερομηνία = the date

This is because Greek often expresses X of Y by putting the second noun in the genitive case.

• λήξη = expiry / expiration (basic dictionary form, nominative)
• λήξης = of expiry / of expiration (genitive singular)

So:

• η ημερομηνία λήξης = literally the date of expiry

This is a very common Greek structure. English often uses noun + noun (expiration date), but Greek commonly uses noun + genitive.

Yes, it is a very common set phrase, especially on food, medicine, cards, and official documents. It means:

• expiration date
• expiry date

You will often also see it without the article in labels or headings:

• Ημερομηνία λήξης: = Expiration date:

But in a full sentence, η is perfectly natural:

• Η ημερομηνία λήξης είναι αύριο.

είναι is the verb to be, and here it means is.

• Η ημερομηνία λήξης είναι αύριο. = The expiration date is tomorrow.

In present-tense Greek, είναι is often used just as in English for is/are.

However, Greek sometimes omits the verb to be in headlines, labels, or very informal note-style language. But in a normal full sentence like this, είναι is the standard choice.

Because αύριο here is an adverb meaning tomorrow, not an adjective.

• αύριο = tomorrow
• αυριανός / αυριανή / αυριανό = tomorrow’s / tomorrow-related

In this sentence, the meaning is:

• The expiration date is tomorrow

So the adverb αύριο is exactly what Greek uses.

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

The neutral, straightforward version is:

• Η ημερομηνία λήξης είναι αύριο.

But you could also hear:

• Αύριο είναι η ημερομηνία λήξης.

This gives more emphasis to tomorrow.

Even so, the original sentence is the most natural if you are simply stating the fact.

A rough pronunciation guide is:

• ee ee-meh-roh-mee-NEE-ah LEE-ksees EE-neh AV-ree-oh

A few notes:

• Η is pronounced ee
• ημερομηνία has the stress on -νία
• λήξης has the stress on λή-
• είναι is usually pronounced something like EE-neh
• αύριο is usually AV-ree-oh

The exact sound may vary a little depending on speaking speed and accent.

Greek uses accent marks to show which syllable is stressed.

In this sentence:

• ημερομηνία → stress on νία
• λήξης → stress on λή
• είναι → stress on εί
• αύριο → stress on αύ

Stress matters in Greek pronunciation, so learners should pay attention to these marks.

Yes. ημερομηνία is a feminine noun, so it stays feminine whenever it appears, although its ending may change depending on case.

For example:

• η ημερομηνία = the date
• της ημερομηνίας = of the date

Its gender does not change; only its form may change.

Yes, depending on context.

• Η λήξη είναι αύριο. = The expiry is tomorrow / The expiration is tomorrow.

This is possible if it is already clear what is expiring. But if you specifically want to mention the expiration date, then:

• Η ημερομηνία λήξης είναι αύριο.

is more precise.

Because Greek often expresses of through the genitive case, not with a separate word.

English:

• date of expiry

Greek:

• ημερομηνία λήξης

Here, λήξης already contains the of idea in its ending. So the grammar is built into the noun form itself.

Yes. It is completely natural Greek and would be used in everyday situations, for example:

• talking about food packaging
• medicine
• credit or bank cards
• documents
• tickets or permits

It sounds like normal, standard Modern Greek.