O órgão mostra taxa de emissão e prazo.

O is the masculine singular definite article, equivalent to the.

It is used because órgão is a masculine singular noun:

• o órgão = the agency / the body / the department

In Portuguese, articles are used more often than in English, so starting with o órgão sounds completely normal.

In this kind of sentence, órgão usually means a public body, government agency, official department, or institutional body.

It does not usually mean the musical instrument here, and it also does not mean a body organ in this context.

So depending on the situation, o órgão could refer to:

• a government office
• a regulatory body
• an official agency

Mostra is the 3rd person singular present form of the verb mostrar (to show).

Conjugation:

• eu mostro = I show
• você/ele/ela mostra = you/he/she shows

The subject is o órgão, which is singular, so the verb must also be singular:

• O órgão mostra... = The agency shows...

Because the verb agrees with the subject, not with the things being shown.

Subject:

• O órgão = singular

Objects:

• taxa de emissão
• prazo

So:

• O órgão mostra... is correct

The fact that two items come after the verb does not change the verb form.

Word by word:

• taxa = fee, rate, charge
• de = of
• emissão = issuance, emission

In many administrative contexts, taxa de emissão usually means something like:

• issuance fee
• fee for issuing a document

Even though emissão can sometimes mean emission in other contexts, here it often refers to the act of issuing something officially.

De links two nouns together. Very often it corresponds to of in English.

So:

• taxa de emissão = literally fee of issuance

English often prefers a different structure, such as:

• issuance fee
• issuing fee

This is very common in Portuguese:

• prazo de entrega = delivery time
• cartão de crédito = credit card
• taxa de juros = interest rate

Portuguese often allows nouns to appear without articles when giving information in a general, concise, or list-like way.

So:

• O órgão mostra taxa de emissão e prazo.

sounds like:

• The agency shows issuance fee and deadline/time frame.

In more explicit or more natural everyday phrasing, you might also see:

• O órgão mostra a taxa de emissão e o prazo.

That version is also correct and may sound more complete to many learners.

So the omission of the articles here is not a mistake; it just makes the sentence more compact, especially in official, technical, or interface-style language.

Prazo usually means a deadline, time limit, time frame, or term, depending on context.

It does not simply mean time in the broad sense.

For example:

• prazo de entrega = delivery time frame / delivery deadline
• prazo final = final deadline
• dentro do prazo = within the deadline / on time

In your sentence, prazo probably means the time frame or deadline related to the process being discussed.

Yes. That version is perfectly correct.

Compare:

• O órgão mostra taxa de emissão e prazo.
  More compact, more like a label, notice, or system description.

• O órgão mostra a taxa de emissão e o prazo.
  More explicit and a little more natural in fuller prose.

Portuguese often varies between including and omitting articles depending on style and context.

A rough pronunciation guide is:

• órgão ≈ OR-gown nasalized at the end

Important points:

• ó is a stressed open o
• ã is nasal
• the final o is weak, and the nasal sound carries through the ending

The spelling has two accent marks:

• ó shows stress
• ã shows nasalization

This is one of those words worth listening to from a native speaker, because the nasal vowel is hard to learn from spelling alone.

Yes, especially in an official, administrative, or website/interface context.

It sounds concise and informational, like something you might see in:

• a government portal
• a form
• a service description
• a table or list of requirements

In more conversational Portuguese, speakers might prefer something slightly fuller, such as:

• O órgão mostra a taxa de emissão e o prazo.
• O órgão informa a taxa de emissão e o prazo.

But the original sentence is still natural.