Ο κηδεμόνας εξηγεί την αδικαιολόγητη απουσία.

It is the 3rd person singular present tense of εξηγώ (to explain).

So:

• εγώ εξηγώ = I explain
• εσύ εξηγείς = you explain
• αυτός/αυτή/αυτό εξηγεί = he/she/it explains

Here it matches the singular subject ο κηδεμόνας.

Because Greek articles change according to gender, number, and case.

Here:

• ο = masculine singular nominative
• την = feminine singular accusative

So:

• ο κηδεμόνας is the subject
• την αδικαιολόγητη απουσία is the direct object

Because the verb εξηγεί takes a direct object, and Greek marks direct objects with the accusative case. The article την tells you that this noun phrase is feminine singular accusative.

Also, απουσία looks the same in nominative and accusative singular, so the article is especially important here.

Because it has to agree with απουσία. Greek adjectives agree with the noun they describe in:

• gender
• number
• case

Since απουσία is feminine singular, the adjective is also feminine singular: αδικαιολόγητη.

In this form, the feminine singular nominative and accusative look the same, so the article την helps show the case.

Because article + adjective + noun is a very common Greek pattern for an attributive adjective:

• την αδικαιολόγητη απουσία

Greek can also use another attributive pattern:

• την απουσία την αδικαιολόγητη

But the version in your sentence is the more neutral and common one for learners to recognize.

No. Greek word order is more flexible than English because articles and endings help show each word’s role.

This sentence uses a neutral order:

• Ο κηδεμόνας εξηγεί την αδικαιολόγητη απουσία.

But Greek could also say:

• Την αδικαιολόγητη απουσία εξηγεί ο κηδεμόνας.

That changes the emphasis, not the basic meaning.

It can mean either. The Modern Greek present tense often covers both the English:

• simple present: explains
• present continuous: is explaining

The context tells you which translation sounds most natural.

Literally, yes: αδικαιολόγητη means not justified. But in school or administrative contexts, a more natural English equivalent is often unexcused absence.

So the literal meaning and the most natural translation may differ slightly.

Yes. Greek often leaves out subject pronouns and even subject nouns when the context makes them clear. The verb form εξηγεί already tells you the subject is he/she/it.

So:

• Εξηγεί την αδικαιολόγητη απουσία. = He/She is explaining the unjustified absence.

Adding Ο κηδεμόνας makes the subject explicit.