Αφού γυρίσω σπίτι, θα βάλω έναν γάντζο πίσω από την πόρτα.

Here, Αφού means after.

So Αφού γυρίσω σπίτι means after I get home / after I return home.

A useful extra note: αφού can also mean since or as/because in other contexts, but in this sentence it is clearly temporal: after.

Γυρίσω is the form Greek uses here for a single completed action in the future.

The idea is:

• first I will return home
• then I will put up the hook

English says after I get home, using a present form. Greek often uses the form γυρίσω in this kind of future-time clause.

Many learners first meet this as the aorist subjunctive form of γυρίζω, although here it appears without να because it follows a conjunction like αφού.

Because Greek normally does not use θα in subordinate time clauses like this.

So Greek says:

• Αφού γυρίσω σπίτι, θα βάλω...
• literally: After I return home, I will put...

Only the main clause needs θα here: θα βάλω.

This is very common in Greek:

• Όταν φτάσω, θα σε πάρω. = When I arrive, I’ll call you.
• Μόλις τελειώσω, θα φύγω. = As soon as I finish, I’ll leave.

In this sentence, it means return, go back, or get back.

The verb γυρίζω has several meanings depending on context, including:

• turn
• return / come back
• go around

With σπίτι, it means go/come back home:

• γυρίζω σπίτι = I go home / I return home
• θα γυρίσω σπίτι = I’ll return home

So here it definitely does not mean turn.

Because γυρίζω σπίτι is a very common idiomatic way to say go/come home.

Greek often uses σπίτι without an article in this expression, just like English often says go home, not go to home.

Compare:

• γυρίζω σπίτι = I go/come home
• γυρίζω στο σπίτι = also possible, but more literally I return to the house/home

So the version in your sentence is very natural and idiomatic.

Because θα βάλω refers to one complete action: putting up/installing the hook.

• βάζω = I put / I am putting / I put habitually
• θα βάλω = I will put

In this sentence, the speaker is talking about a single future action, so θα βάλω is the natural choice.

If you used θα βάζω, it would usually suggest something repeated or ongoing, which does not fit well here.

Literally, yes: βάζω means put.

But in Greek, βάζω is a very broad verb and often covers meanings that English might express with more specific verbs, such as:

• put
• place
• install
• attach
• set

So in this sentence, θα βάλω έναν γάντζο is best understood as something like:

• I’ll put up a hook
• I’ll install a hook
• I’ll attach a hook

Because γάντζος is a masculine noun, and here it is the direct object of θα βάλω, so it appears in the accusative singular.

The forms are:

• nominative: ένας γάντζος = a hook
• accusative: έναν γάντζο = a hook as the object

So:

• Ο γάντζος είναι μεγάλος. = The hook is big.
• Βάζω έναν γάντζο. = I’m putting up a hook.

Because Greek masculine nouns often lose the final -ς in the accusative singular.

So:

• nominative: ο γάντζος
• accusative: τον γάντζο

and with the indefinite article:

• ένας γάντζος
• έναν γάντζο

This is a very normal pattern in Greek.

This whole phrase means behind the door.

It breaks down like this:

• πίσω = back / behind
• από = used here as part of the expression πίσω από = behind
• την πόρτα = the door in the accusative

So:

• πίσω από την πόρτα = behind the door

This is a fixed and very common structure in Greek:

• πίσω από το σπίτι = behind the house
• πίσω από μένα = behind me

Because από takes the accusative, and πίσω από also uses the accusative.

So the noun must be:

• nominative: η πόρτα
• accusative: την πόρτα

That is why the sentence says πίσω από την πόρτα.

Yes, you could, and it would be very natural.

The difference is roughly:

• Όταν γυρίσω σπίτι = When I get home
• Αφού γυρίσω σπίτι = After I get home

In many everyday situations, the difference is small, but αφού makes the sequence a little clearer: first getting home, then putting up the hook.

No, Greek word order is fairly flexible.

Your sentence starts with the time clause:

• Αφού γυρίσω σπίτι, θα βάλω έναν γάντζο πίσω από την πόρτα.

You could also say:

• Θα βάλω έναν γάντζο πίσω από την πόρτα αφού γυρίσω σπίτι.

Both are grammatical. The version with Αφού γυρίσω σπίτι first sounds natural because it sets the time frame before the main action.

Also, when the subordinate clause comes first, Greek normally uses a comma, as in your sentence.