Προτού μπω στη ντουζιέρα, αφήνω το τηλέφωνο στο περβάζι του παραθύρου.

Προτού means before and introduces a time clause.

In this sentence:

• Προτού μπω στη ντουζιέρα = Before I get into the shower

It is very similar to πριν. In everyday Greek, πριν is often more common in speech, but προτού is perfectly natural and a bit more formal or literary in tone.

For example:

• Προτού φύγω, κλείνω τα φώτα.
• Πριν φύγω, κλείνω τα φώτα.

Both mean Before I leave, I turn off the lights.

Because after Προτού, Greek normally uses the subjunctive form, not the regular present indicative.

So:

• μπαίνω = I go in / I enter (dictionary form, present)
• να μπω = that I go in / that I enter (subjunctive form)

After words like προτού, πριν, μόλις, etc., Greek often uses this kind of form for an action that has not happened yet at that point.

So:

• Προτού μπω = Before I go in / before I get in

This is not the same as saying I am entering. It refers to the action as something about to happen.

Yes, this is a very common thing in Greek verbs: the subjunctive / perfective stem can look quite different from the present stem.

For this verb:

• Present form: μπαίνω = I enter / I am entering
• Subjunctive form: να μπω = to enter / that I enter
• Past simple: μπήκα = I entered

So μπω belongs to the same verb, even though it does not look much like μπαίνω.

This is something learners simply need to get used to with some common verbs.

στη is a contraction of:

• σε = in / to / at
• τη = the (feminine accusative singular)

So:

• σε τη ντουζιέρα becomes στη ντουζιέρα

This is standard in modern Greek.

Other common contractions are:

• στο = σε + το
• στον = σε + τον
• στην = σε + την
• στους = σε + τους

Here, στη ντουζιέρα means into the shower or in the shower area, depending on context.

Yes. Ντουζιέρα is a normal modern Greek word meaning shower in the sense of the shower enclosure or shower tray/space.

It is a borrowed word, and many everyday Greek words come from other languages. That is completely normal.

Its gender is feminine, which is why the sentence has:

• στη ντουζιέρα

You may also hear other shower-related expressions, such as:

• κάνω ντους = I take a shower
• μπαίνω στη ντουζιέρα = I get into the shower

Greek often uses the present tense for habitual or regular actions, just like English does.

So:

• αφήνω το τηλέφωνο στο περβάζι του παραθύρου
  = I leave the phone on the windowsill

This can mean:

• That is what I usually do
• That is my routine before showering

If you wanted a one-time future meaning, Greek would usually say something like:

• θα αφήσω το τηλέφωνο... = I will leave the phone...

But in your sentence, the present tense sounds like a general habit.

Here αφήνω means I leave or I put down and leave.

Depending on context, αφήνω can mean:

• leave
• let
• allow
• stop / give up

In this sentence, it clearly means:

• I leave the phone on the windowsill

So the sense is: I place it there and do not take it with me into the shower.

του παραθύρου is in the genitive, and it means of the window.

So:

• το περβάζι = the windowsill / ledge
• του παραθύρου = of the window

Together:

• το περβάζι του παραθύρου = the windowsill

Greek often expresses this kind of relationship with the genitive, where English may use a compound noun instead.

Literally, it is:

• the sill of the window

Natural English translation:

• the windowsill

Because after του, the noun goes into the genitive singular.

Here are the forms:

• το παράθυρο = the window
• του παραθύρου = of the window

This is a very common pattern with neuter nouns.

Another example:

• το βιβλίο = the book
• του βιβλίου = of the book

So παραθύρου is just the genitive form required by the structure.

Because Greek usually does not need subject pronouns unless you want emphasis or contrast.

The verb ending already shows the subject:

• μπω = I enter
• αφήνω = I leave

So Greek naturally says:

• Προτού μπω..., αφήνω...

If you said εγώ, it would usually add emphasis, like:

• I leave the phone there, not someone else.

This is one of the big differences from English.

Yes, Greek word order is fairly flexible, although some versions sound more natural than others.

The original:

• Προτού μπω στη ντουζιέρα, αφήνω το τηλέφωνο στο περβάζι του παραθύρου.

is very natural.

You could also say:

• Αφήνω το τηλέφωνο στο περβάζι του παραθύρου προτού μπω στη ντουζιέρα.

This means the same thing: I leave the phone on the windowsill before I get into the shower.

Greek word order can shift for emphasis, rhythm, or style, but the original version is a very standard way to say it.