Δεν μπορώ να ξεβιδώσω τη βίδα, γιατί την έχω σφίξει πολύ.

In Modern Greek, μπορώ is followed by να + a verb.

So:

• μπορώ να ξεβιδώσω = I can unscrew
• not μπορώ ξεβιδώσω

The word να introduces the dependent verb, roughly like English to in some contexts, though it does not work exactly the same way.

After να, Greek often uses a subjunctive form. In this sentence, ξεβιδώσω is the aorist subjunctive form of ξεβιδώνω.

Here that form suggests a single complete action:

• να ξεβιδώσω = to unscrew it / to get it unscrewed

If you used the present subjunctive instead, να ξεβιδώνω, it would sound more like an ongoing or repeated action, which is not the idea here.

So Δεν μπορώ να ξεβιδώσω τη βίδα means:

• I can’t unscrew the screw
• literally, I can’t manage to unscrew the screw

The prefix ξε- often gives the idea of:

• undoing
• removing
• reversing
• taking apart

So:

• βιδώνω = I screw in / fasten with a screw
• ξεβιδώνω = I unscrew

This is a very useful Greek prefix to learn, because it appears in many verbs with the sense of reversing an action.

τη βίδα is in the accusative, because it is the direct object of the verb ξεβιδώσω.

You are unscrewing the screw, so the screw is what receives the action.

• nominative: η βίδα = the screw
• accusative: τη βίδα = the screw as an object

Greek marks this difference with the article, even when English does not show any change.

This is about the short form of the feminine accusative article/pronoun.

• before a consonant, Greek often uses τη
• before a vowel or in certain phonetic environments, Greek keeps the fuller form την

So:

• τη βίδα
• την έχω σφίξει

The -ν helps the pronunciation flow more smoothly before έχω, which begins with a vowel sound.

You will often see this pattern with both articles and object pronouns.

Here την means it and refers back to τη βίδα.

So the second clause literally says:

• because I have tightened it a lot

Greek uses weak object pronouns like τον, τη(ν), το, τους, τις, τα very often, and they usually come before the verb in ordinary statements.

So:

• την έχω σφίξει
• literally, it I-have tightened
• naturally, I have tightened it

έχω σφίξει is the perfect-like construction in Modern Greek:

• έχω
  • verbal form
• here: έχω σφίξει

It means something like:

• I have tightened it
• I tightened it, and the result still matters now

That is exactly the idea in this sentence: the screw is hard to remove now because of a past action whose result is still relevant.

By contrast:

• έσφιξα = I tightened
• this is more like a simple past event

So την έχω σφίξει πολύ fits the logic very well: it is tight now because of what I did earlier.

It comes from the verb σφίγγω = I tighten / squeeze.

Greek verbs often change stem in different tenses. Here:

• present: σφίγγω
• aorist/perfect stem: σφιξ-
• so: σφίξει

This kind of change is common in Greek and has to be learned as part of the verb’s principal forms.

So it is normal that σφίγγω and σφίξει do not look identical.

In this sentence, πολύ literally means a lot / very much:

• την έχω σφίξει πολύ = I have tightened it a lot

Because the sentence explains a problem, the natural English translation is often too much:

• I can’t unscrew the screw because I tightened it too much

So the Greek word itself is πολύ, but the overall meaning in context is excessive tightening.

If you wanted to make the excess more explicit, Greek could also use things like:

• πάρα πολύ = far too much / very much
• υπερβολικά = excessively

But πολύ is perfectly natural here.

In normal Greek statements, weak object pronouns usually come before the finite verb.

Since έχω is the finite verb here, the pronoun goes before it:

• την έχω σφίξει

not:

• έχω την σφίξει

So even though σφίξει carries the main lexical meaning, the pronoun attaches to the finite part of the verb phrase.

This is a very common Greek pattern and one worth getting used to early.

Yes. Both can mean because.

So these are both possible:

• ... γιατί την έχω σφίξει πολύ
• ... επειδή την έχω σφίξει πολύ

In everyday speech, γιατί is extremely common and natural.

One thing that can confuse learners is that γιατί also means why in questions:

• Γιατί; = Why?

But in this sentence it clearly means because, since it introduces the reason.

Yes, in this sentence it is natural and expected.

Greek uses the definite article more regularly than English. When you are talking about a specific screw in front of you, Greek normally says:

• τη βίδα = the screw

Leaving the article out would usually sound unnatural here unless you were speaking in a very special context, such as labels, instructions, or dictionary-style language.

A Greek speaker would understand it as something like:

• I can’t unscrew the screw because I’ve tightened it too much.

The important ideas are:

• Δεν μπορώ να ξεβιδώσω → I am unable to get it unscrewed
• τη βίδα → the specific screw
• γιατί την έχω σφίξει πολύ → because I tightened it a lot, and that is still the problem now

So the Greek sentence is very natural and idiomatic for describing a present difficulty caused by a past action.