Acordarse de la fecha de la reunión es importante.

Because acordarse de is a fixed Spanish verb pattern meaning to remember.

In this sentence, the verb appears in the infinitive form: acordarse. The -se is not optional here; it is part of the verb as used with this meaning.

Compare:

• acordarse de algo = to remember something
• recordar algo = to remember something

So Spanish often expresses this idea in two common ways:

• Me acuerdo de la fecha.
• Recuerdo la fecha.

Both can mean I remember the date.

Because the verb pattern is acordarse de + noun / pronoun / infinitive.

So you say:

• acordarse de la fecha
• acordarse de eso
• acordarse de llamar

Not:

• acordarse la fecha ❌

That de is required with acordarse when it means to remember.

They do two different jobs:

• acordarse de → this de belongs to the verb
• la fecha de la reunión → this de means of and links date to meeting

So the sentence breaks down like this:

• Acordarse de = to remember
• la fecha de la reunión = the date of the meeting

The first de is grammatical because of the verb. The second de shows a relationship between two nouns.

In Spanish, an infinitive can act like a noun or a noun phrase.

So just as English can say:

• Remembering the date of the meeting is important

Spanish can say:

• Acordarse de la fecha de la reunión es importante

The whole infinitive phrase functions as the subject, and that is why the verb is es.

You can think of it as:

• [To remember the date of the meeting] = subject
• is important = predicate

Yes. That is completely correct.

Both are natural:

• Acordarse de la fecha de la reunión es importante
• Recordar la fecha de la reunión es importante

A useful difference for learners:

• recordar is followed directly by the thing remembered
• acordarse needs de

So:

• recordar la fecha
• acordarse de la fecha

In everyday speech, acordarse de is very common. Recordar may sound a bit more direct or slightly more formal depending on context, but both are normal.

Because Spanish usually uses definite articles with specific nouns in cases like this.

Here we are talking about:

• the specific date
• the specific meeting

So:

• la fecha
• la reunión

This is more natural than leaving the article out.

La fecha de la reunión means the date of the meeting, not just a meeting date in a general sense.

Both are correct, but Es importante acordarse de la fecha de la reunión is often the more natural order in everyday Spanish.

Compare:

• Acordarse de la fecha de la reunión es importante.
• Es importante acordarse de la fecha de la reunión.

The original sentence puts extra focus on remembering the date of the meeting by placing that idea first.

The version starting with Es importante... is often more common in normal conversation and writing.

Because Spanish uses ser with qualities, definitions, and general judgments like important.

So:

• Es importante = It is important

Here, important is not a temporary condition or physical state. It is an evaluation or general fact, so ser is the correct verb.

Here are the present-tense forms:

• me acuerdo
• te acuerdas
• se acuerda
• nos acordamos
• os acordáis
• se acuerdan

Examples:

• Me acuerdo de la fecha.
• ¿Te acuerdas de la reunión?
• Nos acordamos de todo.

Notice the stem change o → ue in most forms:

• acuerdo, acuerdas, acuerda, acuerdan
• but acordamos, acordáis

That is very common in Spanish stem-changing verbs.

Yes, and this is a very common source of confusion.

• acordar algo can mean to agree/decide something
• acordarse de algo means to remember something

Examples:

• Acordaron la fecha de la reunión. = They agreed on the date of the meeting.
• Se acordaron de la fecha de la reunión. = They remembered the date of the meeting.

So the reflexive form plus de changes the meaning.

Yes. In English, Spanish infinitives often match either:

• to remember...
• remembering...

So this sentence can naturally be understood as either:

• To remember the date of the meeting is important
• Remembering the date of the meeting is important

That is normal. Spanish infinitives are flexible in this kind of structure.

Yes. Spanish often switches between an infinitive structure and a que + subjunctive structure depending on whether the subject is general or specific.

General statement:

• Es importante acordarse de la fecha de la reunión.

Specific person:

• Es importante que te acuerdes de la fecha de la reunión.

The first means something like It is important to remember the date of the meeting in general. The second means It is important that you remember the date of the meeting.

So if you want to mention who needs to remember it, que + subjunctive is often the better choice.