Η εξήγηση του διευθυντή ήταν σύντομη και ξεκάθαρη, αλλά εγώ απορώ γιατί άλλαξε ξαφνικά το πρόγραμμα.

Η εξήγηση is the subject of the first clause, so εξήγηση is in the nominative singular.

• η = the, feminine singular nominative
• εξήγηση = explanation, feminine singular nominative

Greek nouns have grammatical gender, and εξήγηση is feminine, so it takes η in the nominative singular.

Του διευθυντή is in the genitive, because it shows a relationship like of the director or the director’s.

So:

• η εξήγηση του διευθυντή = the director’s explanation / the explanation of the director

Forms here:

• ο διευθυντής = the director, nominative
• του διευθυντή = of the director, genitive

This is a very common Greek pattern for possession or close association.

Ήταν is the imperfect of είμαι (to be). Here it means was.

So:

• είναι = is
• ήταν = was

It is used because the sentence is describing a situation in the past: the explanation was short and clear.

They are adjectives agreeing with εξήγηση, which is feminine singular nominative.

So the adjectives must match it in:

• gender
• number
• case

That is why we get:

• σύντομη
• ξεκάθαρη

Compare some typical forms:

• σύντομος = masculine
• σύντομη = feminine
• σύντομο = neuter

and

• ξεκάθαρος = masculine
• ξεκάθαρη = feminine
• ξεκάθαρο = neuter

Και simply means and. It links the two adjectives:

• σύντομη και ξεκάθαρη = short and clear

Greek often uses και exactly where English uses and to connect two qualities.

Yes. Greek often omits subject pronouns because the verb ending already shows the person.

So απορώ by itself already means I wonder / I’m puzzled.

Here εγώ is included for emphasis or contrast:

• ..., αλλά εγώ απορώ ... = ..., but I am wondering ...
• It gives a sense like but as for me... or but I still wonder...

So εγώ is not required for grammar; it is used for tone and emphasis.

Απορώ literally means something like:

• I wonder
• I am puzzled
• I can’t understand

It is in the present tense, first person singular:

• απορώ = I wonder / I’m puzzled

In this sentence it expresses the speaker’s current reaction: the explanation was clear, but I still wonder why something happened.

Γιατί can mean either why or because, depending on context.

Here it means why, because it introduces an indirect question after απορώ:

• απορώ γιατί... = I wonder why...

When γιατί means because, it usually answers a question or gives a reason. Context tells you which meaning is intended.

This is very common in Greek, so learners often need to get used to one word covering both ideas.

Άλλαξε is the aorist form of αλλάζω.

• αλλάζω = I change / I am changing
• άλλαξε = changed

The aorist is normally used for a completed event in the past. Here it points to the fact that the change happened as a single event.

This is a very good question, because το πρόγραμμα can look the same in both the nominative and the accusative.

So in isolation, άλλαξε το πρόγραμμα can be ambiguous:

• the schedule/program changed
• he/she changed the schedule/program

Why? Because:

• άλλαξε can mean changed
• το πρόγραμμα has the same form for nominative and accusative neuter singular

In real usage, the context or the translation usually makes it clear which meaning is intended.

Greek word order is more flexible than English word order.

So άλλαξε το πρόγραμμα is normal Greek. The subject or object can come after the verb, especially when the speaker wants a natural flow or a certain emphasis.

English usually prefers a more fixed order, but Greek often allows:

• verb + noun
• noun + verb

without sounding unusual.

Ξαφνικά is an adverb meaning suddenly.

Here it modifies άλλαξε and tells you how / in what manner the change happened.

Greek adverbs are often fairly movable, so you may also see similar placements like:

• άλλαξε ξαφνικά το πρόγραμμα
• ξαφνικά άλλαξε το πρόγραμμα

Both are natural, though the rhythm or emphasis may shift slightly.

The sentence has two main parts joined by αλλά (but):

1. Η εξήγηση του διευθυντή ήταν σύντομη και ξεκάθαρη
2. αλλά εγώ απορώ γιατί άλλαξε ξαφνικά το πρόγραμμα

So the structure is:

• a statement about the explanation
• followed by a contrasting personal reaction

The contrast is important: even though the explanation was short and clear, the speaker still has a question or doubt.