La reunión empieza en unas dos horas.

In Spanish, it is very common to use the definite article with nouns when talking about a specific thing already understood in context. La reunión means the meeting.

If you said just reunión, it would sound incomplete here unless it were part of a different structure.

• La reunión empieza... = The meeting starts...

Empieza comes from the verb empezar, meaning to start or to begin.

Here it is in the third person singular present tense because the subject is la reunión, which is singular:

• yo empiezo = I start
• tú empiezas = you start
• él/ella empieza = he/she starts
• la reunión empieza = the meeting starts

Also notice the stem change:

• empezar → empieza

This is a common type of verb change in Spanish.

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

• La reunión empieza en unas dos horas.
• The meeting starts in about two hours.

This sounds natural in Spanish. You could also use a future form, but the present is very common for planned events.

Here, en means in, referring to time from now until something happens.

• empieza en dos horas = starts in two hours

This is different from using en for location, as in en Madrid = in Madrid. Spanish uses the same word for both ideas.

Unas here means about, approximately, or some. So:

• en dos horas = in two hours
• en unas dos horas = in about two hours

It makes the time less exact.

This use of unos/unas before a number is very common in Spanish when giving an approximation:

• unos veinte minutos = about twenty minutes
• unas tres semanas = about three weeks

Because horas is a feminine plural noun.

Spanish words like uno/una/unos/unas have to agree with the noun they describe:

• unas horas because horas is feminine plural
• unos minutos because minutos is masculine plural

So:

• unas dos horas = about two hours

Yes. Como dos horas is also a common way to say about two hours.

So these are both natural:

• en unas dos horas
• en como dos horas

In Spain, en unas dos horas is perfectly normal and often sounds a bit more neutral or standard.

You could also say La reunión comienza en unas dos horas. Both empezar and comenzar mean to begin.

• empieza = starts / begins
• comienza = begins / starts

In everyday speech, empezar is often more common, but both are correct.

The accent mark shows where the stress goes: reu-nión.

Without the accent, Spanish pronunciation rules would suggest a different stress pattern. The written accent tells you that the last syllable is stressed.

So:

• reunión → stress on -ón

A natural Spanish version would still often be:

• La reunión empieza en unas dos horas.

Spanish does not always match English progressive forms word for word. Even if English uses is starting, Spanish often just uses the simple present.

If you really want a progressive structure, está empezando usually means it is starting right now, so it would not fit well with en unas dos horas.

No. In this sentence, en unas dos horas means in about two hours from now.

If you want to say for about two hours, Spanish usually uses durante or another structure depending on context:

• La reunión dura unas dos horas. = The meeting lasts about two hours.

So be careful:

• empieza en unas dos horas = starts in about two hours
• dura unas dos horas = lasts about two hours

Yes, you can. Spanish word order is more flexible than English.

Both are correct:

• La reunión empieza en unas dos horas.
• Empieza la reunión en unas dos horas.

The first version is the most neutral here. The second may sound slightly more focused on the action or more conversational depending on context.