Τα φωνητικά είναι δυνατά.

Τα is the definite article, meaning the.

In this sentence, it is:

• neuter
• plural
• nominative (because it goes with the subject)

It matches φωνητικά, so the two go together as τα φωνητικά.

It is plural.

A helpful comparison:

• το φωνητικό = singular
• τα φωνητικά = plural

The ending -ά is a very common ending for neuter plural words in Greek.

Here it is functioning as a noun.

In Greek, forms like this can sometimes come from an adjective but be used as a noun when the article is present. So τα φωνητικά behaves as a noun phrase.

That is very common in Greek: an adjective-looking form can be used substantively, especially with an article.

Είναι is the present-tense form of to be used for both:

• he/she/it is
• they are

So Greek does not distinguish is and are here the way English does.

Examples:

• Το φωνητικό είναι δυνατό. = singular
• Τα φωνητικά είναι δυνατά. = plural

In both sentences, the verb is είναι.

Because it agrees with φωνητικά.

Δυνατά is the adjective, and Greek adjectives must agree with the noun they describe in:

• gender
• number
• case

Here:

• φωνητικά = neuter plural
• δυνατά = neuter plural

So the matching form is required.

Dictionary form:

• δυνατός = strong / loud Matching neuter forms:
• δυνατό = neuter singular
• δυνατά = neuter plural

Because it is a predicate adjective, not an adjective directly attached before the noun.

Compare:

• Τα φωνητικά είναι δυνατά.
  = The adjective comes after είναι and describes the subject.

• Τα δυνατά φωνητικά ...
  = Here the adjective is directly attached to the noun, like the loud vocals/sounds...

So in your sentence, δυνατά is part of the predicate: are loud/strong.

In Greek, δυνατά can also be an adverb in other sentences, often meaning something like loudly.

For example:

• Μιλάει δυνατά. = He/She speaks loudly.

But in Τα φωνητικά είναι δυνατά, it is not an adverb.
Here it is an adjective, because it describes τα φωνητικά after the verb είναι.

So the structure tells you what it is doing.

A simple pronunciation guide is:

ta fo-ni-TI-ka EE-ne dhi-na-TA

A few useful points:

• φ sounds like f
• δ sounds like th in this
• ει in είναι sounds like ee
• the stress is shown by the accent marks:
  • φωνητικά
  • είναι
  • δυνατά

A more accurate pronunciation is roughly: [ta foniˈtika ˈine ðinaˈta]

Yes, they matter.

In Modern Greek, the accent mark shows which syllable is stressed:

• φωνητικά → stress on the last syllable
• είναι → stress on the first syllable
• δυνατά → stress on the last syllable

If you ignore stress, your Greek may still be understood, but it will sound less natural and can sometimes create confusion.

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

The most neutral version is:

• Τα φωνητικά είναι δυνατά.

But you could also say:

• Δυνατά είναι τα φωνητικά.

That version puts more emphasis on δυνατά.

Even though Greek allows movement, the original order is the most straightforward and natural for a learner to use first:

• article + noun + verb + adjective

The singular version would be:

Το φωνητικό είναι δυνατό.

Notice how everything changes to singular:

• τα → το
• φωνητικά → φωνητικό
• δυνατά → δυνατό

This is a good example of agreement in Greek:

• article agrees with noun
• adjective agrees with noun

Usually, yes.

Greek uses the definite article very often, sometimes more often than English does. If you are talking about a specific set of things, τα is the natural choice.

Without the article, the sentence would sound different and may feel incomplete or less natural depending on context.

So for a normal sentence like this, τα φωνητικά is the expected form.