La reunió començarà després de dinar.

Because reunió is a feminine noun in Catalan, so it takes the feminine singular article la.

• la reunió = the meeting
• plural: les reunions = the meetings

The ending -ió is very often feminine in Catalan, though as with all noun patterns, there are exceptions in the language as a whole.

Reunió means meeting.

A helpful pronunciation guide is roughly:

• re-u-ni-Ó
• the stress falls on the last syllable because of the accent mark: -ó

A rough English-friendly approximation would be reh-oo-nee-OH, but with a clearer, shorter vowel quality than in English.

Començarà is the simple future form of començar (to begin / to start).

So:

• comença = begins / is beginning
• va començar = began
• començarà = will begin

In this sentence, the future is being used because the meeting has not started yet:

• La reunió començarà després de dinar.
• The meeting will begin after lunch.

Catalan usually forms the simple future by adding endings directly to the infinitive.

For començar:

• començaré = I will begin
• començaràs = you will begin
• començarà = he/she/it will begin
• començarem = we will begin
• començareu = you all will begin
• començaran = they will begin

So here, començarà agrees with la reunió, which is third person singular.

The accent mark shows where the stress goes: co-men-ça-RÀ.

Without getting too technical, Catalan uses accent marks both to mark stress and sometimes to distinguish vowel quality. In començarà, the accent tells you the last syllable is stressed.

This is very useful because future forms often have that final stress:

• parlarà
• arribarà
• sortirà
• començarà

Després de means after.

It is a fixed expression:

• després de dinar = after lunch / after eating lunch
• després de classe = after class
• després de la reunió = after the meeting

So the de is required here.

Here, dinar is being used in a very natural Catalan way to refer to lunch or having lunch, without an article.

So:

• després de dinar = after lunch / after having lunch

Catalan often uses meal words this way in set expressions:

• abans d’esmorzar = before breakfast
• després de dinar = after lunch
• abans de sopar = before dinner

If you say després del dinar, that usually sounds more like after the lunch / after the meal, referring to a more specific lunch event.

It can be understood as either, and that is part of why the expression feels so natural.

• As a noun, dinar = lunch
• As a verb, dinar = to have lunch / to eat lunch

In després de dinar, learners often understand it as something like:

• after lunch
• or literally after having lunch

Both ideas fit well here.

Catalan usually does not need an explicit subject pronoun when the verb form already makes the subject clear.

Here, the subject is the noun phrase La reunió, and començarà is a third person singular form that matches it.

Catalan often leaves pronouns out unless they are needed for emphasis or contrast.

This is the most normal, neutral order:

• Subject + verb + time expression

So:

• La reunió = subject
• començarà = verb
• després de dinar = time phrase

You could move things around for emphasis, for example:

• Després de dinar, la reunió començarà.

That is also correct, but it sounds more marked or organized around the time expression.

Yes, but it usually means something slightly different.

• després de dinar = after lunch / after eating lunch
• després del dinar = after the lunch / after the meal

So the version with del tends to refer to a specific lunch, while the version in your sentence is the more general and natural everyday phrasing.

A rough pronunciation guide is:

lah reh-oo-nee-OH kuh-men-sah-RAH duh-SPRES duh dee-NAR

A few helpful points:

• reunió is stressed on the last syllable
• començarà is also stressed on the last syllable
• ç in començarà sounds like s
• després is stressed on the second syllable

A more natural rhythm would group it like this:

La reunió / començarà / després de dinar.

In most everyday contexts, començar can mean both begin and start.

So these are both good translations:

• The meeting will begin after lunch.
• The meeting will start after lunch.

In normal usage, there is usually no important difference here.