Απόψε κάνω υπερωρία στο γραφείο, αλλά αύριο έχω ρεπό.

Απόψε means tonight.

It is an adverb, so it gives the time of the action. A very close alternative is σήμερα το βράδυ, literally today in the evening.

In many situations, they mean almost the same thing:

• Απόψε κάνω υπερωρία. = I’m working overtime tonight.
• Σήμερα το βράδυ κάνω υπερωρία. = same basic idea

Απόψε is just more compact and very natural in everyday Greek.

In Greek, κάνω υπερωρία is the normal expression for I do/work overtime.

Literally:

• κάνω = I do / I make
• υπερωρία = overtime

So Greek uses a light verb + noun structure here, where English often prefers a single verbal expression:

• κάνω υπερωρία = work overtime
• literally: do overtime

This is very common in Greek. You will often see κάνω used in expressions where English uses a more specific verb.

υπερωρία means overtime.

It refers to working extra hours beyond the normal schedule. In this sentence, κάνω υπερωρία means the speaker has to stay and work longer than usual.

You may also see it in the plural:

• κάνω υπερωρίες = I do overtime / I work overtime hours

Both singular and plural can appear, depending on context.

στο is a contraction of σε + το.

So:

• σε = in / at / to
• το = the
• σε + το = στο

Therefore:

• στο γραφείο = at the office / in the office

This contraction is completely standard in Greek:

• στο σπίτι = at home / to the house
• στο σχολείο = at school / to the school

It is in the accusative case.

After σε and its contracted forms such as στο, Greek uses the accusative:

• το γραφείο = nominative/accusative neuter singular
• στο γραφείο = at/to the office

Because γραφείο is a neuter noun, the form looks the same in nominative and accusative, so you do not see a visible change here.

Greek often leaves out the article in expressions of this kind.

So:

• κάνω υπερωρία = I work overtime not usually
• κάνω την υπερωρία in this general sense

If you add an article, the meaning usually becomes more specific:

• κάνω την υπερωρία που μου ζήτησαν = I’m doing the overtime they asked me to do

Without the article, it is the general activity.

αλλά means but.

It links two contrasting ideas:

• Απόψε κάνω υπερωρία στο γραφείο = Tonight I’m working overtime at the office
• αλλά αύριο έχω ρεπό = but tomorrow I’m off / I have a day off

It often appears between the two clauses, just like but in English.

αύριο means tomorrow.

Yes, Greek word order is flexible, so it can move for emphasis. For example:

• Αλλά αύριο έχω ρεπό.
• Αλλά έχω ρεπό αύριο.

Both are possible. The version in your sentence is very natural because it highlights the time contrast:

• Απόψε ... αλλά αύριο ...

That is simply the normal Greek expression.

• έχω = I have
• ρεπό = day off / shift off / time off

So έχω ρεπό means:

• I’m off tomorrow
• I have tomorrow off
• I have a day off tomorrow

English and Greek package this idea differently, but the Greek expression is very common and natural.

ρεπό means day off, especially in a work-schedule context.

It is extremely common in everyday Greek. If someone works shifts or has scheduled days off, ρεπό is the normal word you will hear.

It is not slang, but it is more everyday and practical than a very formal phrase. A more formal way to express the idea might use words like άδεια in some contexts, but ρεπό is the right everyday choice here.

Because in Greek, some common expressions use a noun without an article, especially after verbs like έχω.

So:

• έχω ρεπό = I have a day off / I’m off
• έχω δουλειά = I have work
• έχω χρόνο = I have time

The noun is being used in a general, idiomatic way rather than referring to one specific, already identified item.

Greek, like English, can use the present tense for present or near-future situations when the time is clear from context.

Compare in English:

• I’m working overtime tonight, but I’m off tomorrow.

Greek does the same thing:

• Απόψε κάνω υπερωρία...
• αύριο έχω ρεπό.

The time words Απόψε and αύριο make it clear when the actions apply, so the present tense sounds natural.

More or less, yes:

• Απόψε = Tonight
• κάνω = I do
• υπερωρία = overtime
• στο γραφείο = at the office
• αλλά = but
• αύριο = tomorrow
• έχω = I have
• ρεπό = day off

A very literal version would be: Tonight I do overtime at the office, but tomorrow I have a day off.

A more natural English translation would be: Tonight I’m working overtime at the office, but tomorrow I’m off.

Yes, it is normal Greek punctuation here.

The sentence has two coordinated clauses joined by αλλά:

• Απόψε κάνω υπερωρία στο γραφείο
• αλλά αύριο έχω ρεπό

Putting a comma before αλλά is standard and helps show the contrast clearly.

A simple pronunciation guide is:

A-PO-pse KA-no i-pe-ro-RI-a sto gra-FI-o, a-LA AV-rio E-ho re-PO.

A few stress points to notice:

• Απόψε → stress on -πό-
• κάνω → stress on κά-
• υπερωρία → stress on -ρί-
• γραφείο → stress on -εί-
• αλλά → stress on the second α
• αύριο → stress on αύ-
• έχω → stress on έ-
• ρεπό → stress on -πό

Listening to native audio is especially useful here, because words like αύριο and υπερωρία can be tricky at first.

Yes, you may hear that too, and it is understandable.

However, κάνω υπερωρία is one of the most standard and common ways to express work overtime. So for a learner, it is a very good phrase to remember exactly as it is.

A very useful takeaway is to learn these chunks as complete expressions:

• Απόψε = tonight
• κάνω υπερωρία = work overtime
• στο γραφείο = at the office
• αύριο = tomorrow
• έχω ρεπό = have a day off / be off

If you remember the sentence in chunks rather than word by word, it will sound much more natural when you speak Greek.