O vocalista quer ensaiar hoje.

O is the definite article, meaning the. Portuguese often uses articles more regularly than English.

So o vocalista means the vocalist / the lead singer. Without the article, vocalista would usually sound less complete in a normal standalone sentence.

In many real contexts, Portuguese speakers might also omit the subject entirely and just say Quer ensaiar hoje, if it is already clear who they mean.

The article shows grammatical gender:

• o vocalista = the male vocalist
• a vocalista = the female vocalist

A useful detail: vocalista ends in -ista, and nouns of this type often have the same form for masculine and feminine. The article tells you the gender.

So:

• o vocalista = male
• a vocalista = female

Quer is the third-person singular present tense of the verb querer (to want).

Conjugation in the present:

• eu quero = I want
• você/ele/ela quer = you/he/she wants
• nós queremos = we want
• vocês/eles/elas querem = you/they want

In O vocalista quer ensaiar hoje, quer matches o vocalista, which is third-person singular: he wants.

After querer, Portuguese normally uses another verb in the infinitive.

Pattern:

• querer + infinitive

Examples:

• Quero sair. = I want to leave.
• Ela quer estudar. = She wants to study.
• O vocalista quer ensaiar hoje. = The vocalist wants to rehearse today.

So ensaiar stays in its base form because it follows quer.

In English, we say wants to rehearse. In Portuguese, after querer, you usually do not add a separate word for to.

So:

• quer ensaiar not
• quer de ensaiar not
• quer para ensaiar

This is just how the verb works in Portuguese: querer + infinitive.

Ensaiar usually means to rehearse or to practice for a performance.

It is especially common for:

• music
• theater
• dance
• performances
• speeches or presentations

So for a vocalist, ensaiar is very natural, because it suggests practicing a performance, not just doing general exercise or study.

They can both relate to practice, but they are not used in exactly the same way.

• ensaiar = to rehearse, especially for a performance
• praticar = to practice in a broader sense

Examples:

• A banda vai ensaiar. = The band is going to rehearse.
• Eu pratico português todos os dias. = I practice Portuguese every day.

For musicians preparing songs, ensaiar is usually the best choice.

Yes, hoje can move around.

Your sentence:

• O vocalista quer ensaiar hoje.

Also possible:

• Hoje, o vocalista quer ensaiar.
• O vocalista hoje quer ensaiar.
  (possible, but less neutral in many contexts)

The most natural neutral version is often:

• O vocalista quer ensaiar hoje.

Putting hoje at the beginning can add a little emphasis to today.

Yes. Portuguese is often a pro-drop language, meaning the subject can be omitted when it is understood from context.

So you might hear:

• Quer ensaiar hoje.

That can mean He/She wants to rehearse today, depending on context.

However, including the subject is useful when:

• you want to be clear about who you mean
• you are introducing new information
• there could be ambiguity

So O vocalista quer ensaiar hoje is perfectly natural and clear.

A rough pronunciation guide:

• quer ≈ kehr
  The r at the end is usually soft in Brazilian Portuguese.

• ensaiar ≈ en-sah-YAR
  The stress falls on the last syllable.

• hoje ≈ OH-zhee or OH-zheh, depending on accent
  The j sounds like the s in measure.

Very roughly, the whole sentence sounds like:

oo voh-kah-LEES-tah kehr en-sah-YAR OH-zhee

Pronunciation varies by region, but this is a good Brazil-oriented approximation.

Not exactly.

• cantor / cantora = singer
• vocalista = vocalist, often the lead singer of a band

In many contexts they can overlap, but vocalista often sounds more specific to a group or band setting.

So if you are talking about a band rehearsal, vocalista is a very natural choice.

Yes. Quer is present tense: wants.

Portuguese often uses the present tense for something that is true now or planned for today.

So O vocalista quer ensaiar hoje means that, at this moment, the vocalist has the desire/intention to rehearse today.

If you wanted a future idea, you could also say:

• O vocalista vai ensaiar hoje. = The vocalist is going to rehearse today.

But that means something slightly different:

• quer ensaiar = wants to rehearse
• vai ensaiar = is going to rehearse

Not with o vocalista as written, because that clearly means the vocalist.

But the verb form quer can also go with:

• você
• ele
• ela
• o senhor
• a senhora

For example:

• Você quer ensaiar hoje? = Do you want to rehearse today?
• Ele quer ensaiar hoje. = He wants to rehearse today.

So quer is a very common third-person singular form, and in Brazilian Portuguese it also matches você.