Το ύψος του τοίχου είναι δύο μέτρα.

That is a very common point of confusion. In Greek, noun endings often give you a clue about gender, but they do not determine it by themselves.

Ύψος is a neuter noun, so its article is το: το ύψος.

There are quite a few neuter nouns ending in -ος, for example:

• το μέρος
• το λάθος
• το έδαφος

So it is best to learn Greek nouns together with their article:

• το ύψος
• ο τοίχος
• το μέτρο

That way, you automatically learn the gender too.

Here, του does not mean his.

In του τοίχου, του is the genitive singular definite article, so the phrase means of the wall.

So:

• ο τοίχος = the wall
• του τοίχου = of the wall

It is true that του can also mean his in other contexts, but here it is clearly the article because it comes directly before the noun τοίχου.

Because Greek usually expresses this idea with the genitive case instead of a separate word.

English says:

• the height of the wall

Greek says:

• το ύψος του τοίχου

Literally, the idea of of the wall is built into του τοίχου through case marking.

So instead of using a separate preposition like of, Greek changes the form of the noun and article.

Because the noun has to go into the genitive singular.

The basic form is:

• ο τοίχος = the wall

But after το ύψος, Greek needs of the wall, so it becomes:

• του τοίχου

This is a very common pattern for masculine nouns in -ος:

• ο δρόμος → του δρόμου
• ο άνθρωπος → του ανθρώπου
• ο τοίχος → του τοίχου

So -ος often changes to -ου in the genitive singular.

Because the subject of the sentence is το ύψος, which is singular.

The structure is:

• Το ύψος = the height → subject
• είναι = is
• δύο μέτρα = two meters → complement

So the verb agrees with το ύψος, not with δύο μέτρα.

It works the same way in English:

• The height is two meters.
• The price is two euros.

Even though two meters and two euros are plural, the subject is singular, so the verb is singular.

Because after δύο, Greek normally uses the plural noun.

So:

• ένα μέτρο = one meter
• δύο μέτρα = two meters
• τρία μέτρα = three meters

This is very straightforward: anything above one normally takes the plural.

Also, δύο itself does not change here. It stays δύο with masculine, feminine, and neuter nouns in ordinary Modern Greek usage.

In this sentence, δύο μέτρα is the normal form used after είναι to state a measurement.

So Greek says:

• Το ύψος του τοίχου είναι δύο μέτρα.

Here, δύο μέτρα is the natural measurement phrase.

You can see μέτρων in a different structure, for example:

• τοίχος ύψους δύο μέτρων

That means something like a wall of height two meters or a two-meter-high wall.

So:

• είναι δύο μέτρα = normal predicate after είναι
• ύψους δύο μέτρων = a different, more compact/formal construction

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

The sentence as given:

• Το ύψος του τοίχου είναι δύο μέτρα.

is the most neutral, straightforward version.

You could also say:

• Δύο μέτρα είναι το ύψος του τοίχου.

This is understandable, but it puts more emphasis on δύο μέτρα.

So the original order is the best one for a simple, neutral statement.

No. A very natural alternative is:

• Ο τοίχος έχει ύψος δύο μέτρα.

Literally: The wall has height two meters.

This is also very common and natural Greek.

Another, somewhat more formal or written-style version is:

• Ο τοίχος είναι ύψους δύο μέτρων.

So the original sentence is perfectly good, but it is not the only possible way to express the idea.

A rough pronunciation is:

• to IP-sos tou TEE-hou EE-ne THEE-o ME-tra

A more accurate IPA version is:

• /to ˈip.sos tu ˈti.xu ˈi.ne ˈði.o ˈme.tra/

Main stress falls on:

• ύψος
• τοίχου
• είναι
• δύο
• μέτρα

So if you are reading it aloud, those are the syllables to emphasize.