Η στάχτη και τα κάρβουνα είναι μακριά από τα σπίρτα.

Both forms exist, but στάχτη is the standard/common Modern Greek form for ash. It is a feminine singular noun, so it takes the feminine singular article η in the nominative:

• η στάχτη = the ash

A learner may also hear related forms in speech or regional use, but στάχτη is the form to learn first.

Because the nouns have different gender and number:

• η στάχτη = feminine singular
• τα κάρβουνα = neuter plural
• τα σπίρτα = neuter plural

Greek articles have to match the noun’s gender, number, and case. So:

• η = feminine singular nominative
• τα = neuter plural nominative/accusative

It is singular. In Greek, στάχτη usually works like an uncountable noun, much like ash in English.

So:

• η στάχτη = the ash

Even though English can sometimes use ashes, Greek often uses the singular noun στάχτη for the substance in general.

Κάρβουνα is the plural of κάρβουνο. It means coals or pieces of charcoal/coal.

So:

• το κάρβουνο = the coal / a piece of charcoal
• τα κάρβουνα = the coals / the charcoal pieces

In many everyday contexts, Greek naturally uses the plural when talking about multiple hot coals or pieces of charcoal.

Because in Modern Greek, the present tense form είναι can mean both:

• he/she/it is
• they are

So in this sentence, even though the subject is effectively compound (the ash and the coals), the verb is still είναι.

Examples:

• Η στάχτη είναι... = The ash is...
• Τα κάρβουνα είναι... = The coals are...
• Η στάχτη και τα κάρβουνα είναι... = The ash and the coals are...

Here μακριά functions as an adverb/predicative expression, meaning far or far away. It does not agree with the noun in gender or number, so it stays the same.

That is why Greek says:

• είναι μακριά = is/are far away

Whether the subject is singular or plural, μακριά does not change:

• Το σπίτι είναι μακριά.
• Τα σπίτια είναι μακριά.

Από means from. In this sentence, it is used with μακριά to mean far from:

• μακριά από = far from

So:

• μακριά από τα σπίρτα = far from the matches

This is a very common Greek combination.

After από, Greek normally uses the accusative case. However, with neuter plural nouns, the nominative and accusative forms are often identical.

So:

• nominative: τα σπίρτα
• accusative: τα σπίρτα

They look the same, even though the grammatical role is different.

The singular is:

• το σπίρτο = the match

The plural is:

• τα σπίρτα = the matches

Because these are two separate nouns, and each noun normally keeps its own article:

• η στάχτη = the ash
• τα κάρβουνα = the coals

This is especially necessary here because the nouns have different gender/number combinations. Greek usually does not try to share one article across unlike nouns.

So η στάχτη και τα κάρβουνα is the natural way to say the ash and the coals.

• Η στάχτη and τα κάρβουνα are in the nominative, because they are the subject of the sentence.
• Τα σπίρτα is in the accusative, because it follows the preposition από.

So the structure is:

• Subject (nominative): Η στάχτη και τα κάρβουνα
• Verb: είναι
• Expression: μακριά από τα σπίρτα

Yes. Greek word order is more flexible than English word order, although the given version is the most neutral and straightforward:

• Η στάχτη και τα κάρβουνα είναι μακριά από τα σπίρτα.

You could also move parts around for emphasis, for example:

• Μακριά από τα σπίρτα είναι η στάχτη και τα κάρβουνα.

That said, the original order is the best one for a learner to use first.

A simple pronunciation guide:

• Η στάχτη ≈ ee STAH-khtee
• και ≈ keh
• τα κάρβουνα ≈ ta KAR-voo-na
• είναι ≈ EE-ne
• μακριά ≈ ma-kree-AH
• από ≈ a-PO
• τα σπίρτα ≈ ta SPEER-ta

A few useful notes:

• χ in στάχτη is a rough sound, like the ch in Scottish loch or German Bach
• The written accent shows the stressed syllable:
  • στάχτη
  • κάρβουνα
  • μακριά
  • σπίρτα

Σπίρτο / σπίρτα is a common Modern Greek word for match / matches, and it is a loanword. For most learners, the important thing is simply to recognize and use it correctly:

• το σπίρτο = the match
• τα σπίρτα = the matches

Like many loanwords in Greek, it has been fully integrated into normal Greek grammar.