Περνάω το πάτωμα στο σαλόνι πριν έρθουν οι καλεσμένοι.

Yes, περνάω / περνώ very often means pass, go past, or spend time. But in everyday Greek it can also mean go over a surface with something, so with cleaning contexts it can mean wipe, mop, or go over.

So Περνάω το πάτωμα literally suggests I go over the floor, and idiomatically it means I mop / wipe the floor.

This is a very common kind of verb extension in Greek: a basic motion verb develops a practical everyday meaning like go over something with a cloth, mop, brush, etc.

Yes. Περνάω and περνώ are two forms of the same verb in Modern Greek.

• περνάω is extremely common in everyday speech
• περνώ is also correct and may sound a bit shorter or slightly more formal/literary depending on context

So this sentence could also be written as:

Περνώ το πάτωμα στο σαλόνι πριν έρθουν οι καλεσμένοι.

Both are natural.

Το πάτωμα is in the accusative case because it is the direct object of περνάω.

The speaker is doing the action to the floor:

• περνάω = I mop / wipe
• το πάτωμα = the floor

So Greek marks the thing affected by the action with the accusative.

Also:

• το = neuter singular definite article
• πάτωμα = neuter singular noun

They match in gender, number, and case.

Στο σαλόνι means in the living room.

It is a contraction of:

• σε = in / at / to
• το = the

So:

• σε το → στο

Here it tells us where the floor is:

• το πάτωμα στο σαλόνι = the floor in the living room

In natural English, we would usually say the living-room floor or the floor in the living room.

After πριν meaning before, Modern Greek often uses the subjunctive verb form, and να may be omitted.

So both of these are possible:

• πριν έρθουν
• πριν να έρθουν

In many everyday sentences, leaving out να is very common and natural.

So πριν έρθουν οι καλεσμένοι means before the guests arrive.

The important thing is that the verb after πριν is in the right form; the presence of να is often optional here.

Έρθουν is the aorist subjunctive form of έρχομαι. After πριν in this kind of sentence, Greek normally uses a subjunctive form to refer to an event that has not happened yet.

So:

• έρχονται = they are coming / they come
• έρθουν = they come / arrive, viewed as a single complete event in a subjunctive environment

Here the idea is before the guests arrive, not before they are in the process of coming. Greek prefers the aorist subjunctive because the arrival is seen as a single whole event.

Because the subject is οι καλεσμένοι = the guests, which is plural.

So the verb must agree with that plural subject:

• ο καλεσμένος = the guest
• οι καλεσμένοι = the guests

Therefore:

• έρθει = he/she comes
• έρθουν = they come

Οι καλεσμένοι is in the nominative plural because it is the subject of έρθουν.

Breakdown:

• οι = nominative plural article
• καλεσμένοι = nominative plural masculine form

So in the clause πριν έρθουν οι καλεσμένοι, the guests are the ones performing the action of arriving.

Yes. Καλεσμένος literally means invited or invited person / guest.

It comes from the verb καλώ = call / invite.

So:

• ο καλεσμένος = the invited male person / the guest
• η καλεσμένη = the invited female person / the guest
• οι καλεσμένοι = the guests

In this sentence, the natural English translation is simply the guests.

Good question. The clause πριν έρθουν οι καλεσμένοι does refer to a future event from the speaker’s point of view, but Greek does not use θα after πριν here.

So Greek says:

• πριν έρθουν οι καλεσμένοι

not

• πριν θα έρθουν οι καλεσμένοι

As for the main verb Περνάω, without θα it is formally a present form. Depending on context, that can sound like:

• a habitual action: I mop the living-room floor before the guests arrive
• a current/planned action in informal usage

If you wanted to make the main action clearly future and one-time, you could say:

Θα περάσω το πάτωμα στο σαλόνι πριν έρθουν οι καλεσμένοι.

By itself, Περνάω is a present-tense form, so without extra context it most naturally suggests a habitual or general action:

I mop the living-room floor before the guests arrive.

However, in everyday speech, Greek can sometimes use the present for something happening around now or as an informal near-future statement, depending on context and tone.

If the speaker wants to make the future meaning completely explicit, Greek would often use:

Θα περάσω το πάτωμα στο σαλόνι πριν έρθουν οι καλεσμένοι.

So the exact interpretation depends on context.

Yes, but the nuance is slightly different.

• το πάτωμα στο σαλόνι = the floor in the living room
• το πάτωμα του σαλονιού = the living room’s floor / the floor of the living room

Both are possible. The original version with στο σαλόνι is very natural and conversational. It identifies the floor by location. The version with του σαλονιού is also correct and may sound a bit more explicitly possessive or descriptive.

Yes, Greek word order is more flexible than English word order.

The original:

Περνάω το πάτωμα στο σαλόνι πριν έρθουν οι καλεσμένοι.

is completely natural.

But Greek could also say things like:

• Πριν έρθουν οι καλεσμένοι, περνάω το πάτωμα στο σαλόνι.
• Το πάτωμα στο σαλόνι το περνάω πριν έρθουν οι καλεσμένοι.

These versions shift emphasis slightly:

• putting πριν έρθουν οι καλεσμένοι first emphasizes the time
• putting το πάτωμα στο σαλόνι first emphasizes what gets cleaned

So the original is neutral and straightforward, but other word orders are possible.