Η ένδειξη είναι σωστή.

• Η = the (feminine singular definite article, nominative)
• ένδειξη = a feminine singular noun
• είναι = is
• σωστή = correct (feminine singular adjective)

So the structure is:

article + noun + verb + adjective

That is very normal Greek sentence structure.

Η is the feminine singular form of the definite article, meaning the.

Greek articles change depending on:

• gender
• number
• case

Since ένδειξη is:

• feminine
• singular
• nominative (the subject of the sentence)

the correct article is η.

Compare:

• ο for masculine singular nominative
• η for feminine singular nominative
• το for neuter singular nominative

In this sentence, you can tell because it takes:

• the feminine article η
• the feminine adjective σωστή

Also, many Greek nouns ending in -η or -ση / -ξη are feminine, and ένδειξη follows that pattern.

So even if you had not seen the word before, the rest of the sentence gives you strong clues that it is feminine.

Greek adjectives must agree with the noun they describe in:

• gender
• number
• case

Since ένδειξη is feminine singular nominative, the adjective must also be feminine singular nominative:

• masculine: σωστός
• feminine: σωστή
• neuter: σωστό

So:

• η ένδειξη είναι σωστή not
• η ένδειξη είναι σωστός not
• η ένδειξη είναι σωστό

Είναι is the present tense of to be.

In Modern Greek, είναι is used for:

• he/she/it is
• they are

So Greek does not distinguish between is and are in the 3rd person the way English does.

Examples:

• Η ένδειξη είναι σωστή. = The indication/reading is correct.
• Οι ενδείξεις είναι σωστές. = The indications/readings are correct.

Sometimes in informal speech, Greek can omit forms of to be, especially in headlines, labels, or very compressed speech. But in a normal full sentence like this, είναι is the standard and natural form.

So:

• Η ένδειξη είναι σωστή. = normal full sentence

You may occasionally see shortened styles in special contexts, but learners should use είναι here.

A rough pronunciation is:

ee EN-thee-ksee EE-neh so-STEE

A more careful approximation:

• Η = ee
• ένδειξη = EN-dhee-ksee or EN-thee-ksee depending on pronunciation style
• είναι = EE-ne
• σωστή = so-STEE

A few useful notes:

• η is pronounced ee
• ει is also pronounced ee in Modern Greek
• the accent marks show where the stress goes:
  • ένδειξη
  • είναι
  • σωστή

That is just part of the noun’s normal form. Many Greek feminine nouns end in -ξη, such as:

• λέξη = word
• πράξη = act/action
• τάξη = class/order

So ένδειξη belongs to a common noun pattern. For a learner, the important thing is to recognize that nouns of this type are typically feminine.

Yes. Greek word order is more flexible than English because the endings and articles give grammatical information.

The neutral, most straightforward order is:

• Η ένδειξη είναι σωστή.

But Greek can change the order for emphasis, for example:

• Σωστή είναι η ένδειξη.
• Είναι σωστή η ένδειξη.

These can sound more marked or emphatic depending on context. For learners, the original order is the safest and most neutral.

The plural would be:

Οι ενδείξεις είναι σωστές.

Changes:

• Η → Οι (the, plural)
• ένδειξη → ενδείξεις (plural noun)
• σωστή → σωστές (plural feminine adjective)
• είναι stays είναι

So this is a good example of how the article, noun, and adjective all change together, while είναι does not.

Not only. σωστός / σωστή / σωστό can mean:

• correct
• right
• proper

Its exact meaning depends on context.

So Η ένδειξη είναι σωστή. could mean something like:

• the reading is correct
• the indication is correct
• the displayed value is right

The grammar stays the same either way.

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

You can see that from:

• the nominative article η
• the sentence structure: the indication is correct

In Greek, the nominative is typically used for the subject.

So here:

• Η ένδειξη = the subject
• είναι σωστή = what is being said about it

Because this is a normal statement, and Greek uses the same period/full stop as English: .

A useful punctuation note for learners:

• Greek uses ; as a question mark
• Greek uses · as a semicolon-like mark in more formal writing

So:

• Η ένδειξη είναι σωστή. = statement
• a Greek question would end with ; not ? in standard Greek typography