Datamos el documento ayer.

In this sentence, datar means to date a document. Depending on context, that can mean either:

• to put a date on it
• to determine what date it belongs to

It is related to the English word date, but in Spanish it can sound a bit more formal or technical.

Because datamos is one of those Spanish forms that can be either present or preterite for nosotros.

So datamos can mean:

• we date (present)
• we dated (preterite)

The word ayer makes it clear that this sentence is talking about the past, so here it means we dated.

Without ayer, the form would be ambiguous.

No. In Spanish, the subject pronoun is often omitted because the verb ending already shows who is doing the action.

So:

• Datamos el documento ayer.
• Nosotros datamos el documento ayer.

Both are correct, but the version without nosotros is more normal unless you want emphasis, contrast, or clarity.

For example, you might say Nosotros datamos el documento, no ellos to stress we.

Because el documento is the direct object of the verb.

With datar, you date something, so Spanish uses the direct object without a:

• datar el documento
• firmar el documento
• leer el documento

Al is a + el, and it would not be used here.

Also, the personal a is mainly used before specific people, and documento is not a person.

In standard Spanish, especially in Spain, ayer normally goes with the preterite because it refers to a finished action in a finished time period.

So the natural choice is:

• Datamos el documento ayer.

Not usually:

• Hemos datado el documento ayer.

In Spain, the present perfect is more commonly used with time expressions connected to the present, such as:

• hoy
• esta semana
• este mes

So you are more likely to hear:

• Hoy hemos datado el documento.

Yes. Spanish word order is fairly flexible.

All of these are possible:

• Datamos el documento ayer.
• Ayer datamos el documento.
• Datamos ayer el documento.

The most neutral version here is probably Datamos el documento ayer. Putting ayer first can give it slightly more emphasis.

That depends on the exact context.

In Spain, fechar is often very natural when you mean to put a date on a document. Datar is also correct, but it can sound a bit more formal, technical, or broader in meaning.

So both may appear, but:

• fechar un documento = often used for writing the date on it
• datar un documento = can also mean assigning or identifying its date

A learner may hear fechar quite a lot in practical, administrative contexts.

It is pronounced roughly da-TA-mos, with the stress on the second syllable.

There is no written accent because Spanish stress rules already predict that pronunciation: words ending in a vowel, n, or s are normally stressed on the second-to-last syllable.

So:

• datamos → stress on ta

Also, in normal Spanish pronunciation, the d between vowels is softer than the English d.

Yes, datar is a regular -ar verb.

That means it follows normal patterns, for example:

• yo dato
• tú datas
• él/ella data
• nosotros datamos
• vosotros datáis
• ellos datan

And in the preterite:

• yo daté
• tú dataste
• él/ella dató
• nosotros datamos
• vosotros datasteis
• ellos dataron

Notice that nosotros datamos is the same in both the present and the preterite, which is why context words like ayer are so important.