É normal que você fique nervoso antes da prova.

Because que introduces a subordinate clause: É normal que... = It’s normal that...

In Portuguese, after impersonal expressions like é normal, é importante, é bom, é possível, etc., you often get this pattern:

É + adjective + que + clause

So:

É normal que você fique nervoso
literally: It’s normal that you get/feel nervous

Because é normal que usually requires the subjunctive in Portuguese.

Fique is the present subjunctive form of ficar for você / ele / ela.

This happens because the sentence is not simply stating a plain fact; it expresses a judgment or evaluation: it is normal that...

Compare:

• Você fica nervoso antes da prova. = You get nervous before the test.
  → more like a straightforward statement of fact
• É normal que você fique nervoso antes da prova. = It’s normal for you to get nervous before the test.
  → evaluation/opinion, so subjunctive

Here, ficar nervoso means to get nervous, to become nervous, or sometimes simply to feel nervous.

The verb ficar often means to become when followed by an adjective:

• ficar feliz = to become happy
• ficar triste = to become sad
• ficar nervoso = to become/get nervous

So even though ficar can also mean to stay, that is not the best interpretation here.

Yes, in Brazilian Portuguese that version is also common and natural.

There is a small difference in structure:

• É normal que você fique nervoso...
  → uses que + subjunctive
• É normal você ficar nervoso...
  → uses an infinitive clause

Both are used, but É normal que você fique... sounds a bit more formal or more traditionally grammatical in careful writing. In everyday speech, É normal você ficar... is very common.

Because the adjective agrees with the person being described.

• If you are speaking to a man: você fique nervoso
• If you are speaking to a woman: você fique nervosa

So the sentence changes depending on who você refers to.

Yes, it could be omitted if the context makes it clear:

É normal que fique nervoso antes da prova.

However, in Brazilian Portuguese, subject pronouns like você are used more often than in European Portuguese, so keeping você sounds very natural.

Also, since fique could mean you, he, or she, using você makes the sentence clearer.

Because de + a contracts to da in Portuguese.

Here the expression is antes de = before.
When de is followed by the feminine article a, they combine:

• de + a = da
• de + o = do
• de + as = das
• de + os = dos

So:

• antes da prova = before the test
• not antes de a prova

Because the form changes depending on what comes next:

• antes de + noun
• antes de + infinitive verb

Examples:

• antes da prova = before the test
• antes de fazer a prova = before taking the test

In your sentence, prova is a noun, and it has the article a, so de + a = da.

It is the present subjunctive.

For ficar, the present subjunctive forms are:

• eu fique
• você/ele/ela fique
• nós fiquemos
• vocês/eles/elas fiquem

Even though it is called present subjunctive, it does not always mean present time. In this sentence, it refers to a general situation: getting nervous before the test.

Yes, É normal literally means It is normal.

Portuguese often uses impersonal expressions without an explicit subject pronoun like English it. So where English says:

• It is normal
• It is important
• It is possible

Portuguese simply says:

• É normal
• É importante
• É possível

The it is understood, but not spoken.