Há uma reunião importante hoje à tarde.

In this sentence, há comes from the verb haver and means there is or there are.

So:

• Há uma reunião = There is a meeting
• Há duas reuniões = There are two meetings

In this use, haver is impersonal, so it does not agree with the noun after it.

This is a very common way to express existence in Portuguese, especially in neutral or more formal language.

Yes. With impersonal haver, the verb stays in the singular.

Examples:

• Há uma reunião importante.
• Há duas reuniões importantes.
• Há muitos problemas.

Even though English changes from there is to there are, Portuguese keeps há the same in this structure.

Yes. In everyday Brazilian Portuguese, tem is extremely common in speech to mean there is / there are.

So these are both natural:

• Há uma reunião importante hoje à tarde.
• Tem uma reunião importante hoje à tarde.

The difference is mostly tone:

• há = more formal, more written, more standard
• tem = very common in conversation

A learner should understand both.

In Portuguese, adjectives usually come after the noun.

So the most neutral order is:

• uma reunião importante

Putting the adjective before the noun is possible, but it sounds more literary, expressive, or stylistically marked:

• uma importante reunião

That version is not wrong, but it is less neutral than the original sentence.

Because reunião is a feminine noun in Portuguese, so it takes:

• uma reunião
• a reunião

This is something you mostly have to learn with the noun itself. The ending -ão does not always tell you the gender, because nouns ending in -ão can be masculine or feminine.

For example:

• o pão = masculine
• a reunião = feminine

Because hoje already means today, and in Portuguese it normally does not need a preposition.

So you say:

• hoje
• hoje de manhã
• hoje à tarde
• hoje à noite

Not:

• em hoje ❌

This is similar to English, where you usually just say today, not on today.

À tarde means in the afternoon or, in this sentence, more naturally this afternoon.

The à is not just a normal accent mark. It shows crasis, which is the contraction of:

• preposition a
• article a

So:

• a + a = à

This happens in many time expressions:

• à tarde
• à noite
• às três horas

The grave accent in à is important in writing.

They are different.

• à tarde = in the afternoon
• a tarde = the afternoon

Examples:

• Há uma reunião hoje à tarde. = There is a meeting this afternoon.
• A tarde está linda. = The afternoon is beautiful.

So the accent changes the function and the meaning.

A helpful breakdown is:

• re-u-ni-ÃO

The stress is on the last syllable: -ão.

A rough English-friendly guide is something like:

• reh-oo-nee-OW̃

A few pronunciation notes:

• The r at the beginning in Brazilian Portuguese is usually pronounced like a soft h sound.
• The ending -ão is nasal, which is very common in Portuguese.
• The letters e and u are pronounced separately here, so reu is not one single English-style sound.

The h is silent, so há is pronounced simply like ah, with stress on that vowel.

The accent mark helps distinguish it in writing from other forms and shows the stressed vowel.

So:

• há sounds like ah

Yes, in most contexts that is the most natural translation.

Literally, it is something like:

• today in the afternoon

But in English, the normal way to say that is:

• this afternoon

So in this sentence, hoje à tarde is best understood as this afternoon.

Yes. Portuguese allows some flexibility.

For example, you could also say:

• Hoje à tarde há uma reunião importante.

That sounds natural too. The meaning stays basically the same, but the focus shifts a little:

• Há uma reunião importante hoje à tarde. → starts by presenting the existence of the meeting
• Hoje à tarde há uma reunião importante. → starts by emphasizing the time

Both are correct.

It is grammatically possible, but it is less natural in this context than há or tem.

• há = very standard for existence
• tem = very common in spoken Brazilian Portuguese
• existe = possible, but often sounds more like you are emphasizing that something exists

So a Brazilian would more naturally say:

• Há uma reunião importante hoje à tarde.
• Tem uma reunião importante hoje à tarde.

rather than Existe uma reunião importante hoje à tarde, unless there is some special emphasis.

Very simply:

Negative:

• Não há uma reunião importante hoje à tarde.
• More naturally in many contexts: Não há reunião importante hoje à tarde.

Question:

• Há uma reunião importante hoje à tarde?

In Portuguese, yes/no questions are often shown just by intonation in speech and by the question mark in writing.