Ένας σωρός ρούχων είναι στο πάτωμα.

Ένας means a or one.

Greek indefinite articles change for gender:

• ένας = masculine
• μία / μια = feminine
• ένα = neuter

Here it is ένας because σωρός (pile, heap) is a masculine noun.

So:

• ένας σωρός = a pile
• not μία σωρός
• not ένα σωρός

Σωρός means pile, heap, or sometimes stack, depending on context.

In this sentence, ένας σωρός ρούχων means a pile of clothes.

It is a very common word in everyday Greek. You may also hear it more figuratively, for example:

• Έχω ένα σωρό δουλειές. = I have a pile / tons of things to do.

So in your sentence, it is the literal meaning: a physical pile of clothes.

Because Greek expresses a pile of clothes as:

• σωρός
  • genitive plural

So:

• ρούχα = clothes (nominative/accusative plural)
• ρούχων = of clothes (genitive plural)

Literally, the phrase is:

• ένας σωρός ρούχων = a pile of clothes

This is very common after nouns like pile, group, glass, box, etc., where English often uses of and Greek often uses the genitive.

Yes.

The basic noun is:

• το ρούχο = the item of clothing / garment

Its plural is:

• τα ρούχα = clothes

And the genitive plural is:

• των ρούχων = of the clothes

In your sentence, there is no article before ρούχων, so you just get:

• ρούχων = of clothes

This gives the indefinite sense a pile of clothes, not a pile of the clothes.

Because the subject of the sentence is ένας σωρός (a pile), not ρούχων.

So Greek grammar treats the whole phrase as centered on σωρός, which is singular:

• Ένας σωρός ρούχων είναι...
• literally: A pile of clothes is...

English works the same way:

• A pile of clothes is on the floor not
• A pile of clothes are on the floor
  (though some speakers may say that informally)

So the singular verb is completely normal.

Στο is a contraction of:

• σε = in, at, on, to
• το = the (neuter singular)

So:

• σε το → στο

In this sentence:

• στο πάτωμα = on the floor

This contraction is extremely common in Modern Greek:

• στο σπίτι = in the house / at home
• στο τραπέζι = on the table
• στο σχολείο = at school

In Modern Greek, σε normally takes the accusative, even when it means location.

So:

• στο πάτωμα = on the floor
• literally: in/on the floor

The noun here is το πάτωμα (the floor), which is neuter. In the singular, neuter nominative and accusative often look the same, so you see:

• nominative: το πάτωμα
• accusative: το πάτωμα

That is why the form does not visibly change.

Greek often simply uses the normal verb to be:

• Ένας σωρός ρούχων είναι στο πάτωμα.
• literally: A pile of clothes is on the floor.

That is a perfectly natural way to express the idea.

Greek can also use structures equivalent to there is/are, especially with υπάρχει / υπάρχουν:

• Υπάρχει ένας σωρός ρούχων στο πάτωμα.
• There is a pile of clothes on the floor.

So both patterns exist, but your sentence uses the straightforward X is on Y structure.

Yes. Greek word order is more flexible than English.

Your sentence:

• Ένας σωρός ρούχων είναι στο πάτωμα.

Other possible orders include:

• Στο πάτωμα είναι ένας σωρός ρούχων.
• Ένας σωρός ρούχων στο πάτωμα είναι.
  This one is possible in special contexts, but less neutral.

The most neutral version here is the original one. Moving στο πάτωμα to the front can give more emphasis to the location:

• On the floor, there is a pile of clothes.

So the order can change, but not all versions sound equally natural in every context.

In normal speech, you would usually include ένας here.

• Ένας σωρός ρούχων είναι στο πάτωμα. = natural, complete
• Σωρός ρούχων είναι στο πάτωμα. = unusual in isolation

Greek often uses the article where English might omit it. Since you are introducing a pile, ένας sounds most natural.

You might omit the article in special styles, headlines, notes, or very compressed speech, but for a learner, it is best to keep ένας.

Because ρούχων here is indefinite and means of clothes in a general sense.

• ένας σωρός ρούχων = a pile of clothes
• ένας σωρός των ρούχων = a pile of the clothes

The version with των would only make sense if you were talking about specific clothes already known from context, and even then it may sound more formal or less natural depending on the situation.

So for the ordinary meaning a pile of clothes, the version without the article is the normal one.

A simple pronunciation guide is:

É-nas so-RÓS RÚ-hon Í-ne sto PÁ-to-ma

A few notes:

• Ένας → stress on the first syllable
• σωρός → stress on the last syllable
• ρούχων → stress on ρού-
• είναι is often pronounced roughly like EE-ne
• πάτωμα → stress on πά

The χ in ρούχων is not like English ch. It is a throat sound, like the German Bach or Scottish loch, though after ου many speakers pronounce it a bit softer.

Yes. It is grammatical and natural.

A native speaker might also say:

• Υπάρχει ένας σωρός ρούχα στο πάτωμα.
  This can occur informally in speech, though it is less careful grammatically.
• Υπάρχει ένας σωρός ρούχων στο πάτωμα.
• Έχει ένα σωρό ρούχα στο πάτωμα.
  More colloquial, depending on context.

But your sentence,

• Ένας σωρός ρούχων είναι στο πάτωμα. is a solid, standard sentence and very good for learning.