A rainha chegou cedo.

Because Portuguese does not use a as the indefinite article. In Portuguese:

• a = the (feminine singular definite article)
• uma = a / an (feminine singular indefinite article)

So A rainha means the queen, while Uma rainha would mean a queen.

Because rainha is a feminine noun. In Portuguese, articles must agree with the noun’s grammatical gender:

• a rainha = the queen
• o rei = the king

This is grammatical gender, which is a normal part of Portuguese grammar. It does not always match biological sex in every noun, but here it does.

In Brazilian Portuguese, rainha is roughly pronounced ha-EEN-ya or ra-EEN-ya, depending on the regional r sound.

A few helpful points:

• It has 3 syllables: ra-i-nha
• nh sounds like ny in canyon
• The stress is on the middle syllable: ra-IN-ha

So a good approximation is ra-EEN-ya.

Chegou is the pretérito perfeito (simple past) of chegar.

So:

• chegar = to arrive
• chegou = arrived

It refers to a completed action in the past. In this sentence, the queen’s arrival is presented as a finished event.

In Brazilian Portuguese, chegou is roughly sheh-GOH.

Helpful details:

• ch sounds like sh
• g before o is a hard g
• The stress is on the last syllable: che-GOU

So: sheh-GOH.

Because the subject is already stated: A rainha.

Portuguese does not need an extra subject pronoun when the subject noun is present. In fact, adding ela here would usually sound unnecessary:

• A rainha chegou cedo. = natural
• A rainha, ela chegou cedo. = possible in some contexts, but marked or emphatic

So the normal sentence just uses the noun phrase by itself.

Here, cedo is an adverb.

It modifies the verb chegou, telling us when the queen arrived. So it means early in the sense of arrived early.

Compare:

• A rainha chegou cedo. → cedo modifies the verb
• É cedo. → cedo can also function in expressions meaning it is early

Because cedo is an adverb here, and adverbs do not agree with nouns in gender or number.

So even though rainha is feminine singular, cedo stays the same:

• A rainha chegou cedo.
• As rainhas chegaram cedo.

The noun and article change, but cedo does not.

That is the most neutral and natural word order in this sentence.

Portuguese often places adverbs like cedo after the verb:

• A rainha chegou cedo.

You can move it for emphasis, but that changes the feel:

• Cedo, a rainha chegou. = more marked, more literary, or emphatic
• A rainha cedo chegou. = unusual in everyday speech

So the original order is the standard one.

Normally, no—not in standard everyday Portuguese.

With a common noun as the subject, Portuguese usually wants an article or another determiner:

• A rainha chegou cedo. = normal
• Rainha chegou cedo. = sounds incomplete, telegraphic, or like a headline

You would usually only omit the article in special styles or structures, not in an ordinary sentence like this.