O xerife chegou cedo.

O means the. It is the masculine singular definite article in Portuguese.

So:

• o xerife = the sheriff

Portuguese usually uses articles more often than English does, so seeing o here is completely normal.

Because xerife is treated as a masculine noun in Portuguese.

• o = masculine singular
• a = feminine singular

So the correct form is:

• o xerife = the sheriff

If you were talking about a feminine noun, you would normally use a instead.

Chegou is the verb chegar in the third person singular of the simple past (also called the preterite).

Here it means:

• he arrived
• she arrived
• it arrived
• or, with the noun, the sheriff arrived

So:

• O xerife chegou. = The sheriff arrived.

Portuguese verbs change form depending on the subject, so a single verb form carries grammatical information.

In this sentence:

• chegou matches ele/ela/você or a singular noun like o xerife

That is why Portuguese does not need an extra helping verb here.

Cedo means early, and here it functions as an adverb.

Portuguese often places adverbs like this after the verb:

• chegou cedo = arrived early

This word order is very natural in Portuguese.

Here it is an adverb, because it describes how/when he arrived.

• O xerife chegou cedo. = The sheriff arrived early.

In other contexts, cedo can relate to the idea of earliness in time, but in this sentence you should understand it as the adverb early.

In Brazilian Portuguese, xerife is pronounced approximately like:

• she-REE-fee

A rough guide:

• xe sounds like she
• ri sounds like ree
• fe sounds like fee

So:

• xerife ≈ she-REE-fee

In Portuguese, the letter x can have different pronunciations depending on the word. In xerife, it has the sh sound.

So:

• x in xerife = sh

This is something learners usually have to memorize word by word, because x is not always pronounced the same way in Portuguese.

In Brazilian Portuguese, chegou is pronounced approximately:

• sheh-GOH

A rough breakdown:

• che sounds like sheh
• gou sounds like goh

The stress falls on the last syllable:

• che-GOU

Because the subject is already expressed with the noun o xerife.

• O xerife chegou cedo.

There is no need to add ele. In fact, saying both would usually sound unnecessary unless you wanted special emphasis.

In standard Portuguese, O xerife chegou cedo is the most natural way to say The sheriff arrived early.

Dropping the article can sound incomplete or unnatural in ordinary usage, unless you are using Xerife like a title, name, or in a special style such as headlines.

So for normal learning purposes, use:

• O xerife chegou cedo.

It is past tense, specifically the preterite.

So it means:

• arrived

Not:

• arrives
• is arriving

If you wanted present tense, you would use:

• chega = arrives

The dictionary form is chegar, which means to arrive.

Some common forms are:

• chegar = to arrive
• chega = arrives
• chegou = arrived

So chegou comes from chegar.

Yes, in this case it is very similar:

• O xerife = the sheriff
• chegou = arrived
• cedo = early

So the structure is:

• Subject + verb + adverb

That makes this sentence quite straightforward for an English speaker.

Yes. When you say the place someone arrived at/to, Portuguese often uses a.

For example:

• O xerife chegou à cidade cedo. = The sheriff arrived in the city early.

Here, a + a = à.

But in your sentence, no destination is mentioned, so you simply have:

• O xerife chegou cedo.

Yes, it is completely natural and correct.

A Brazilian Portuguese speaker would easily understand it as:

• The sheriff arrived early.

It is short, grammatical, and idiomatic.