Η σωστή διάγνωση είναι πολύ σημαντική για την ανάρρωση.

Η is the feminine singular definite article in the nominative case, so here it means the.

It matches διάγνωση (diagnosis), which is a feminine singular noun and the subject of the sentence:

• Η σωστή διάγνωση = the correct diagnosis

Greek articles change depending on gender, number, and case, so the is not always the same word.

Because σωστή has to agree with διάγνωση.

The adjective σωστός (correct/right) changes form to match the noun:

• σωστός = masculine
• σωστή = feminine
• σωστό = neuter

Since διάγνωση is feminine, the adjective must also be feminine:

• η σωστή διάγνωση = the correct diagnosis

This kind of agreement is very important in Greek.

It is in the nominative case, because it is the subject of the sentence.

The full subject is:

• Η σωστή διάγνωση = the correct diagnosis

The sentence structure is:

• Η σωστή διάγνωση = subject
• είναι = is
• πολύ σημαντική = very important
• για την ανάρρωση = for recovery

σημαντική is the feminine singular form of the adjective σημαντικός / σημαντική / σημαντικό (important).

It agrees with the thing being described, which is η σωστή διάγνωση. Since that phrase is feminine singular, the adjective is also feminine singular:

• Η σωστή διάγνωση είναι πολύ σημαντική.
• The correct diagnosis is very important.

Even though σημαντική comes after είναι, it still matches the subject in gender and number.

είναι means is and is the 3rd person singular form of είμαι (to be).

So:

• Η σωστή διάγνωση είναι πολύ σημαντική
  = The correct diagnosis is very important

Greek often uses είναι just like English uses is in this kind of sentence.

In normal standard Greek, you usually keep it here.

You may sometimes see omission of είναι in:

• headlines
• notes
• very informal style
• emphatic or poetic language

But for learners, the normal and correct full sentence is:

• Η σωστή διάγνωση είναι πολύ σημαντική για την ανάρρωση.

So in this sentence, it is best to think of είναι as required.

πολύ means very here. It modifies the adjective σημαντική:

• πολύ σημαντική = very important

So:

• σημαντική = important
• πολύ σημαντική = very important

Be careful: πολύ can also mean much/a lot, depending on context, but here it clearly means very.

Greek often uses the definite article more often than English does.

So while English says:

• for recovery

Greek naturally says:

• για την ανάρρωση
• literally: for the recovery

This does not necessarily mean one specific recovery in a super-literal sense. It is just the natural Greek way to express the idea.

Because για takes the accusative case, and ανάρρωση is the object of για.

So the feminine singular article changes:

• η = nominative
• την = accusative

That is why you get:

• για την ανάρρωση = for the recovery / for recovery

This is a very common pattern in Greek:

• η διάγνωση
• τη διάγνωση
• για τη/την διάγνωση

It is in the accusative case, because it follows the preposition για.

So:

• η ανάρρωση = nominative
• την ανάρρωση = accusative

In this sentence:

• για την ανάρρωση = for recovery

Many Greek prepositions are followed by the accusative, and για is one of the most common ones.

ανάρρωση means recovery, especially in a medical or health-related sense.

So in this sentence it refers to the patient’s recovery or getting better.

Related idea:

• αναρρώνω = to recover

So ανάρρωση is the noun, while αναρρώνω is the verb.

Not completely. Greek word order is more flexible than English word order because case endings and articles help show what each word is doing.

The neutral, natural order here is:

• Η σωστή διάγνωση είναι πολύ σημαντική για την ανάρρωση.

But Greek can sometimes move things around for emphasis. For example, you might hear:

• Για την ανάρρωση, η σωστή διάγνωση είναι πολύ σημαντική.

That puts extra focus on recovery.

Still, the original version is the most straightforward and natural for learners.

A rough pronunciation is:

• thee-AGH-no-see

More carefully:

• δι- sounds like thee (in Modern Greek spelling, δια here is pronounced roughly thia / ðia, depending on how you approximate it in English)
• -άγ- has the stress
• γν is pronounced together, roughly like gn in a softened Greek way
• -ωση sounds like -osee

The stressed syllable is marked by the accent:

• διάγνωση

So the stress falls on άγ.

A rough pronunciation is:

• a-NA-ro-see

The stress is on νά, as shown by the accent:

• ανάρρωση

The double ρρ is pronounced as a stronger r sound than a single ρ, though learners do not need to overdo it at first.

Greek uses an accent mark to show which syllable is stressed.

Examples from the sentence:

• σωστή → stress on the last syllable
• διάγνωση → stress on άγ
• σημαντική → stress on κή
• ανάρρωση → stress on νά

Stress matters in Greek pronunciation, so the accent marks are important and should be learned as part of the word.

Yes. σωστός / σωστή / σωστό can mean:

• correct
• right
• proper

In this sentence, correct diagnosis is the most natural translation, but proper diagnosis is also close in meaning depending on context.

The core idea is that the diagnosis is accurate and appropriate.

It follows a very common Greek pattern:

[Subject] + [είναι] + [adjective] + [prepositional phrase]

So here:

• Η σωστή διάγνωση = subject
• είναι = is
• πολύ σημαντική = very important
• για την ανάρρωση = for recovery

This is a useful model for building similar sentences, for example:

• Η καλή θεραπεία είναι σημαντική για τον ασθενή.
  Good treatment is important for the patient.

• Η έγκαιρη διάγνωση είναι πολύ σημαντική.
  Early diagnosis is very important.