Μετά από τόσες ώρες στον υπολογιστή νιώθω μεγάλη κούραση.

Μετά από is the standard Modern Greek way to say after before a noun or time expression.

So:

• μετά από τόσες ώρες = after so many hours

This is very common with periods of time:

• μετά από λίγο = after a little while
• μετά από δύο μέρες = after two days

In this sentence, it introduces the time context first, just like English can do with After so many hours....

Τόσες means so many or that many.

It comes from the word τόσος / τόση / τόσο, which changes form to match the noun it describes.

Here the noun is ώρες:

• ώρα = hour
• ώρες = hours

Because ώρες is:

• feminine
• plural

the matching form is τόσες.

So:

• τόσες ώρες = so many hours

It also often adds the feeling that the speaker thinks the amount is a lot.

Greek often leaves out the article in quantity expressions like this.

So τόσες ώρες is a natural indefinite phrase meaning:

• so many hours

If you added an article, it would sound more specific or emphatic in a different way. For example, τις τόσες ώρες would not be the neutral choice here.

So the version in the sentence is the normal one.

Because υπολογιστή is the accusative singular form.

The basic dictionary form is:

• ο υπολογιστής = the computer

But after σε and after the article τον, Greek uses the accusative:

• στον υπολογιστή = at/on the computer

This is a very common pattern in Greek:

• ο φίλος → τον φίλο
• ο δρόμος → τον δρόμο
• ο υπολογιστής → τον υπολογιστή

So the missing final -ς is a normal case ending change.

Στον is a contraction of:

• σε + τον → στον

So:

• σε = at, in, on, to
• τον = the, masculine accusative singular
• στον = at/in/on/to the

That means:

• στον υπολογιστή = at/on the computer

Greek very often contracts σε + article like this:

• σε το → στο
• σε τη(ν) → στη(ν)
• σε τους → στους

In this sentence, the most natural English sense is at the computer or on the computer.

Greek σε covers several meanings that English splits into different prepositions. So στον υπολογιστή does not mean the speaker is physically inside the computer. It is the normal Greek way to express being engaged with it.

Depending on context, English might translate it as:

• at the computer
• on the computer

Both are fine.

Because Greek usually does not need subject pronouns when the verb ending already shows who the subject is.

Νιώθω means:

• I feel

The ending -ω tells you it is first person singular, so εγώ is unnecessary unless you want emphasis.

So:

• νιώθω = I feel
• εγώ νιώθω = I feel, with extra emphasis or contrast

This is very normal in Greek.

Νιώθω is:

• present tense
• first person singular
• from the verb νιώθω = to feel

So it means:

• I feel
• I am feeling

In this sentence it describes the speaker’s current state after spending many hours at the computer.

Because μεγάλη has to agree with κούραση.

The noun κούραση is:

• feminine
• singular

So the adjective must also be feminine singular:

• μεγάλος = masculine
• μεγάλη = feminine
• μεγάλο = neuter

Therefore:

• μεγάλη κούραση = great / strong / considerable tiredness

Also, in this sentence κούραση is the object of νιώθω, so it is in the accusative, but for many feminine nouns in -η, the nominative and accusative singular look the same.

Greek can express this idea in more than one way.

This sentence uses a noun:

• νιώθω μεγάλη κούραση = I feel great fatigue / strong tiredness

A more directly adjective-based way would be:

• είμαι πολύ κουρασμένος if a man is speaking
• είμαι πολύ κουρασμένη if a woman is speaking

That means I am very tired.

So the given sentence is correct, but it sounds a bit more like describing the feeling of fatigue itself, not just the state tired.

No. It is natural, but not the only option.

Other common ways include:

• νιώθω κούραση = I feel tiredness / fatigue
• νιώθω μεγάλη κούραση = I feel a lot of fatigue
• έχω μεγάλη κούραση = I have great fatigue
• είμαι πολύ κουρασμένος/η = I am very tired

The sentence you have is perfectly understandable and natural, though in everyday speech many people might more often say είμαι πολύ κουρασμένος/η.

Yes, Greek word order is fairly flexible.

The given order:

• Μετά από τόσες ώρες στον υπολογιστή νιώθω μεγάλη κούραση.

puts the time/context first, which is very natural.

You could also say:

• Νιώθω μεγάλη κούραση μετά από τόσες ώρες στον υπολογιστή.

This is also correct.

The difference is mostly about emphasis and flow, not basic meaning. Starting with Μετά από τόσες ώρες... highlights the cause or background first.