A legenda está correta.

A is the feminine singular definite article, equivalent to the.

So A legenda means the caption / the subtitle.

Portuguese uses definite articles more often than English does, so a sentence that would sound natural in English without the may still need a / o / as / os in Portuguese.

Not usually. In Brazilian Portuguese, legenda most often means:

• subtitle (in a video or movie)
• caption (under an image, post, or graphic)
• sometimes legend/key on a map or chart

So it is a false friend if you assume it means the story of a famous hero. For that meaning, Portuguese usually uses lenda.

Examples:

• Ative as legendas. = Turn on the subtitles.
• A legenda da foto está errada. = The photo caption is wrong.

Portuguese often uses estar for a current state or condition, and ser for identity, essence, or more permanent characteristics.

Here, A legenda está correta means the caption/subtitle is correct as it currently stands.

That sounds natural because correctness here is treated as a state of the caption. In other words, you are evaluating it now.

Using é correta is possible in some contexts, but está correta is the more natural everyday choice for checking whether something is right.

A helpful comparison:

• A resposta está correta. = The answer is correct.
• Ela é correta. = She is proper/correct/respectable in behavior.

Because correta has to agree with legenda, which is a feminine singular noun.

In Portuguese, adjectives usually agree in gender and number with the noun they describe.

So:

• a legenda correta = the correct caption
• o texto correto = the correct text
• as legendas corretas = the correct captions
• os textos corretos = the correct texts

That is why you have correta, not correto.

You can tell from the article a and from the adjective correta.

In Portuguese, gender is grammatical, so nouns are classified as masculine or feminine. Legenda is feminine, so it takes:

• a legenda
• a legenda correta

A lot of nouns ending in -a are feminine, though there are exceptions.

The accent mark shows where the stress goes.

Without getting too technical, está is pronounced with stress on the last syllable: es-TÁ.

The accent is important because Portuguese spelling often shows stress patterns. Here it tells you the final syllable is stressed.

So:

• está → stress on tá

A simple approximation for an English speaker is:

ah leh-ZHEN-dah es-TAH koh-HEH-tah

A few notes:

• legenda: the g before e sounds like the s in measure for most Brazilian accents
• está: stress the last syllable
• correta: the double rr is a strong Portuguese r, often like an English h sound in many Brazilian accents

A more natural Brazilian flow may sound roughly like:

a le-ZHEN-da is-TA ko-HE-ta

Pronunciation varies by region, but that is a good starting point.

Yes. Certa is often used in everyday speech with a meaning very close to correct/right.

So both are natural:

• A legenda está correta.
• A legenda está certa.

Very roughly:

• correta can sound a bit more formal or precise
• certa can sound a bit more conversational

In many real situations, the difference is small.

Yes, but A legenda está correta is the normal, neutral order.

You may also hear:

• Está correta a legenda.

That version is more marked or stylistic, and it may sound more formal or emphatic depending on context.

For a learner, the standard pattern is best:

• subject + verb + adjective
• A legenda está correta.

Usually, in standard Portuguese, you would keep the article and say A legenda está correta.

Dropping the article may sound unnatural unless you are speaking in a very abbreviated way, such as notes, interface text, headlines, or highly informal speech.

So for normal sentences, use:

• A legenda está correta.

In A legenda está correta, correta is a predicate adjective.

That means it is linked to the subject by the verb estar:

• subject: A legenda
• verb: está
• adjective: correta

It is not the same structure as:

• A legenda correta = the correct caption

Compare:

• A legenda está correta. = The caption is correct.
• A legenda correta aparece na tela. = The correct caption appears on the screen.

Yes, depending on context.

In Brazilian Portuguese, legenda can mean:

• a subtitle in a film or video
• a caption under a picture, post, or graphic

So A legenda está correta could mean:

• The subtitle is correct.
• The caption is correct.

The surrounding context tells you which one is meant.