O tribunal abre cedo.

In Portuguese, it is very common to use the definite article with nouns when talking about a specific thing or institution.

• o tribunal = the court
• um tribunal = a court

So O tribunal abre cedo sounds like you are talking about a particular court that both speaker and listener can identify.

In some contexts, Portuguese can omit the article, but with a sentence like this, o tribunal is the normal choice.

Because tribunal is a masculine singular noun in Portuguese.

So the article must match:

• o tribunal = masculine singular
• a would be used with a feminine singular noun

Even though a court is not biologically male, Portuguese nouns still have grammatical gender, and tribunal is masculine.

Abre is the third-person singular present tense of the verb abrir (to open).

The verb abrir is conjugated like this in the present tense:

• eu abro
• você / ele / ela abre
• nós abrimos
• vocês / eles / elas abrem

Since o tribunal is a third-person singular subject, the correct form is abre.

Literally, abre means opens.

So O tribunal abre cedo literally means The court opens early.

In natural English, depending on context, this could also be understood as:

• The court opens early
• The court is open early

But grammatically, Portuguese is using the verb to open, not the expression to be open.

If you wanted to say is open, you might say:

• O tribunal está aberto cedo
  This is possible, but it sounds less natural for a general schedule statement.

For opening times and routines, abre is the most natural choice.

Here, cedo is an adverb, meaning early.

It describes when the court opens.

So:

• abre = opens
• cedo = early

Do not confuse this with other uses of cedo. In Portuguese, cedo can also appear in expressions related to soon or early in time, but in this sentence it clearly means early.

Because cedo by itself can function directly as an adverb.

Portuguese often uses simple adverbs without extra words:

• chega cedo = arrives early
• acorda cedo = wakes up early
• abre cedo = opens early

So you do not need de or any other preposition here.

Yes, but O tribunal abre cedo is the most neutral and natural order.

This is the basic pattern:

• subject + verb + adverb

Possible alternatives may appear in special contexts, for example for emphasis, but they are less neutral:

• Cedo, o tribunal abre.
  Possible, but more literary or emphatic.
• O tribunal cedo abre.
  This sounds unnatural in normal Brazilian Portuguese.

So for everyday use, stick with:

• O tribunal abre cedo.

A rough pronunciation guide for Brazilian Portuguese is:

• o = roughly like oo in a short, unstressed way
• tribunal = tree-boo-NAU
• abre = AH-bree
• cedo = SEH-doo or SEH-doh, depending on accent

A rough full version:

oo tree-boo-NAU AH-bree SEH-doo

A few helpful notes:

• The stress in tribunal is on the last syllable: -nal
• The stress in abre is on a
• The stress in cedo is on ce

It can refer to either one, depending on context.

Tribunal may mean:

• the court as an institution
• the court building
• a particular legal body or judicial authority

In a sentence about opening hours, many people will understand it as the place or office opening for the day. But context can make it more institutional too.

Usually, O tribunal abre cedo is understood as a general fact, habit, or schedule:

• The court opens early.
• The court opens early every day.

The Portuguese present tense often covers this kind of general truth or routine.

If you wanted to make right now more explicit, Portuguese would usually add context or use a different structure, depending on what exactly you mean.

If you want to talk about the courts, both the noun and the verb must change:

• Os tribunais abrem cedo. = The courts open early.

Notice the changes:

• o → os
• tribunal → tribunais
• abre → abrem

This is a good example of subject-verb agreement in Portuguese.

Yes, but the meaning changes slightly.

• O tribunal abre cedo. = The court opens early
  A specific court
• Um tribunal abre cedo. = A court opens early
  Any one court, or an unspecified court

So um makes it less specific.

Yes. A few common expansions are:

• O tribunal abre muito cedo. = The court opens very early.
• O tribunal abre às oito. = The court opens at eight.
• O tribunal abre cedo de segunda a sexta. = The court opens early from Monday to Friday.

These follow the same basic structure and are very natural extensions of the original sentence.