La reunión tiene lugar pasado mañana.

Tener lugar is a fixed expression meaning to take place or to be held.

So:

• La reunión tiene lugar... = The meeting takes place...

It is not usually translated word for word, even though tener means to have and lugar means place.

This expression is fairly common in formal or neutral Spanish.

Because the subject is la reunión, which is singular.

• la reunión = the meeting
• one meeting = singular
• so the verb must also be singular: tiene

Compare:

• La reunión tiene lugar pasado mañana. = one meeting
• Las reuniones tienen lugar pasado mañana. = more than one meeting

Spanish often uses the present tense to talk about scheduled or planned future events, just like English sometimes does.

For example:

• La reunión tiene lugar pasado mañana.
• El tren sale mañana.
• Mañana viajamos.

This gives the idea of something arranged or scheduled.

You could also say:

• La reunión tendrá lugar pasado mañana.

That uses the future tense and sounds a bit more formal or explicit.

Pasado mañana is a fixed expression meaning the day after tomorrow.

It should be learned as one chunk. Even though pasado often means past, here the whole expression means:

• mañana = tomorrow
• pasado mañana = the day after tomorrow

A native English speaker should avoid trying to translate it literally as past tomorrow.

Because pasado mañana is being used as a time expression, and in Spanish these expressions often appear without an article.

Compare:

• hoy = today
• mañana = tomorrow
• pasado mañana = the day after tomorrow
• ayer = yesterday

So:

• La reunión tiene lugar pasado mañana. is completely natural.

Adding el here would sound wrong in this sentence.

Yes, it is a bit more formal or official-sounding than some other ways to say the same thing.

You often see it in:

• announcements
• schedules
• news
• official communication

More everyday alternatives include:

• La reunión es pasado mañana.
• La reunión será pasado mañana.
• La reunión se hace pasado mañana. (more colloquial in some contexts, but not always the best choice for a meeting)

So tiene lugar is correct and natural, but it has a slightly formal tone.

Yes. That is also correct.

The difference is mainly one of style:

• tiene lugar = present tense, often used for scheduled events
• tendrá lugar = future tense, slightly more formal or explicit

Both mean basically the same thing here.

Because reunión is a feminine noun in Spanish, so it takes la:

• la reunión

Many nouns ending in -ión are feminine, for example:

• la reunión
• la canción
• la decisión
• la información

Like all nouns in Spanish, grammatical gender is something you usually need to learn together with the word.

The accent mark in reunión shows where the stress goes:

• reu-nión

Without the accent, Spanish spelling rules would suggest a different stress pattern.

The accent helps indicate that the last syllable is stressed. It also reflects the pronunciation clearly.

Yes, but the original order is the most neutral:

• La reunión tiene lugar pasado mañana.

You could also say:

• Pasado mañana tiene lugar la reunión.

That version puts more focus on pasado mañana.

In everyday Spanish, word order can shift for emphasis, but the original sentence sounds very natural and straightforward.

Yes. Pasado mañana is standard and widely used in Latin America as well as in Spain.

It is the normal way to say the day after tomorrow.

So for a learner focusing on Latin American Spanish, this expression is absolutely useful and natural.