Αυτός ο μπελάς είναι σοβαρός.

This is a very common Greek pattern:

demonstrative + article + noun

So:

• Αυτός ο μπελάς = this trouble / this hassle

In English, we just say this trouble, but in Greek the article is normally kept.

A very literal breakdown would be:

• Αυτός = this
• ο = the
• μπελάς = trouble / hassle

Even though English does not say this the trouble, Greek does.

A second common word order is:

• ο μπελάς αυτός

This also means this trouble, but Αυτός ο μπελάς is the more basic pattern for learners.

Yes, it is the same basic word form, but here it is being used as a demonstrative adjective, not as a personal pronoun.

αυτός can mean:

• he when it stands alone
• this when it comes with a noun in patterns like αυτός ο...

So in this sentence:

• Αυτός ο μπελάς = this trouble

It does not mean he the trouble. The structure makes its function clear.

Because μπελάς is a masculine noun in Greek. Grammatical gender in Greek is part of the word itself and does not always match any natural gender idea.

So because μπελάς is masculine singular, the words that go with it must match:

• Αυτός not Αυτή or Αυτό
• ο not η or το
• σοβαρός not σοβαρή or σοβαρό

This is called agreement.

Because adjectives in Greek agree with the noun they describe.

Here, the subject is:

• Αυτός ο μπελάς = masculine singular

So the adjective must also be masculine singular:

• σοβαρός = serious

Compare:

• ο μπελάς είναι σοβαρός = masculine
• η κατάσταση είναι σοβαρή = feminine
• το πρόβλημα είναι σοβαρό = neuter

Even though σοβαρός comes after είναι, it still agrees with the subject.

Because σοβαρός is a predicate adjective here, not an adjective directly attached to a noun.

Compare these two ideas:

1. ο σοβαρός μπελάς = the serious trouble

   • adjective directly modifies the noun
   • article is part of the noun phrase

2. ο μπελάς είναι σοβαρός = the trouble is serious

   • adjective comes after is
   • no article before the adjective

So in Αυτός ο μπελάς είναι σοβαρός, σοβαρός means is serious, not the serious.

Not exactly. Μπελάς often means something like:

• trouble
• hassle
• nuisance
• headache in an everyday sense
• mess or bother

It is usually a bit more colorful and conversational than πρόβλημα.

So:

• πρόβλημα = problem
• μπελάς = trouble / hassle / nuisance

Depending on context, μπελάς can sound more emotional or more colloquial.

The grammar is completely normal and neutral, but μπελάς is a somewhat everyday word.

So the sentence sounds natural in ordinary speech. If you wanted a more neutral or formal noun, you might use πρόβλημα instead:

• Αυτό το πρόβλημα είναι σοβαρό. = This problem is serious.

That said, Αυτός ο μπελάς είναι σοβαρός is perfectly standard Greek.

Yes. Greek word order is more flexible than English, though not completely free.

Possible versions include:

• Αυτός ο μπελάς είναι σοβαρός.
• Ο μπελάς αυτός είναι σοβαρός.

Both are grammatical and mean essentially the same thing.

You can also move things for emphasis, for example:

• Σοβαρός είναι αυτός ο μπελάς.

That sounds more marked, as if stressing serious.

For a learner, Αυτός ο μπελάς είναι σοβαρός is the safest and most straightforward order.

No, not in standard Greek.

With a demonstrative before a noun, Greek normally uses the article:

• Αυτός ο μπελάς
• Αυτή η ιδέα
• Αυτό το πρόβλημα

So Αυτός μπελάς sounds wrong in standard Modern Greek.

The main noun phrase is in the nominative singular masculine because it is the subject of the sentence.

• Αυτός = nominative masculine singular
• ο = nominative masculine singular article
• μπελάς = nominative masculine singular
• σοβαρός = nominative masculine singular adjective

And:

• είναι = is

Greek often shows grammatical relationships through endings, and here the matching masculine singular endings help show that these words belong together.

In Modern Greek, μπ often represents a b sound, especially at the beginning of a word.

So μπελάς is pronounced roughly like:

• beh-LAS

More broadly, the whole sentence is approximately:

• af-TOS o beh-LAS EE-ne so-va-ROS

A few pronunciation notes:

• Αυτός has the stress on the second syllable: -τός
• μπελάς has the stress on the last syllable: -λάς
• είναι is usually pronounced EE-ne
• σοβαρός has the stress on the last syllable: -ρός

Yes, in a normal statement like this, Greek uses the verb είναι = is.

So:

• Αυτός ο μπελάς είναι σοβαρός.

You cannot normally drop είναι in standard neutral prose the way some languages can omit is in the present tense.

In casual speech, people may sometimes shorten or reshape sentences, but for correct standard Greek, keep είναι here.