La réunion a lieu demain.

A lieu comes from the fixed expression avoir lieu, which means to take place or to be held.

So in La réunion a lieu demain, you should understand a lieu as one unit, not word by word.

• a = has / is the il/elle/on form of avoir
• lieu = place

Literally, it is something like has place, but that is not how you should translate it. Learn avoir lieu as a set expression.

Because French uses the idiom avoir lieu for events.

English often says:

• The meeting takes place tomorrow
• The meeting is tomorrow

French commonly says:

• La réunion a lieu demain

So this is not about possession. The meeting is not having a place in the usual sense. It is just the normal French expression for an event happening or being scheduled.

A is the present tense form of avoir.

Even though demain refers to the future, French often uses the present tense for scheduled or clearly planned future events, especially when there is a time word that makes the future meaning obvious.

So:

• La réunion a lieu demain = present form, future meaning from demain

This is very natural in French.

Yes. La réunion aura lieu demain is also correct.

• a lieu = present form, often used for scheduled future events
• aura lieu = future form, more explicitly future

Both are good, but aura lieu can sound a little more formal or more explicitly tied to the future.

So you may see both:

• La réunion a lieu demain
• La réunion aura lieu demain

Yes, in many situations you can.

• La réunion est demain = very natural, common, direct
• La réunion a lieu demain = also natural, but a bit more formal or event-focused

So the difference is not that one is right and the other is wrong. It is more about style and emphasis.

For example:

• La réunion est demain. = The meeting is tomorrow.
• La réunion a lieu demain. = The meeting takes place tomorrow / is being held tomorrow.

Because demain is an adverb meaning tomorrow.

French does not need a preposition like on or at before it.

So you say:

• demain = tomorrow
• demain matin = tomorrow morning
• demain à 9 heures = tomorrow at 9 o’clock

Not:

• à demain in this sentence

Note that À demain ! does exist, but that means See you tomorrow!, which is a different structure.

Because réunion is a feminine noun in French.

That means it takes feminine articles:

• la réunion
• une réunion

This is something you usually have to learn with the noun. Grammatical gender in French does not always match any logical or real-world gender.

So it is best to memorize nouns with their article:

• la réunion
• not le réunion

No. It is used for many kinds of events or proceedings.

For example:

• Le concert a lieu ce soir.
• La cérémonie a lieu samedi.
• La conférence a lieu en ligne.

It is most commonly used for events, especially planned or organized ones. It sounds more natural with things like meetings, concerts, ceremonies, conferences, elections, and similar events than with people or ordinary actions.

A rough English-style guide is:

• réunion ≈ ray-yoo-nyon
• lieu ≈ lyeu

A few helpful notes:

• réunion has four syllables: ré-u-ni-on
• the ending of réunion is nasal, so the final sound is not exactly like English on
• lieu is just one syllable

In the full sentence, there is normally no liaison between réunion and a:

• La réunion a lieu demain

So you pronounce the words separately rather than linking them with a z sound.