Nous attendons trente minutes.

Because attendons is the present-tense, first-person plural form of attendre.

• attendre = the infinitive, to wait
• nous attendons = we wait / we are waiting

The ending -ons is the usual ending for nous in the present tense.

Nous means we.

In standard French, subject pronouns are normally stated, so French usually says both:

• nous = the subject
• attendons = the verb form that matches nous

Even though the verb ending already shows it is we, French still normally keeps the subject pronoun.

In French, attendre can take a length of time directly.

So French says:

• attendre trente minutes

rather than literally translating English wait for thirty minutes with a separate word for for.

This is very common with durations after attendre.

Not exactly.

By itself, Nous attendons trente minutes usually means something like:

• We are waiting thirty minutes
• We wait thirty minutes
• We’ll wait thirty minutes in some contexts

If you want to say We have been waiting for thirty minutes (up to now), French usually says:

• Nous attendons depuis trente minutes.

So depuis is important when the idea is for thirty minutes already.

After a number, French normally uses the noun directly, without an article:

• trente minutes
• deux heures
• cinq jours

So trente minutes is just the normal way to say thirty minutes.

Because the number is more than one.

• une minute = singular
• trente minutes = plural

That is the same basic idea as in English: one minute but thirty minutes.

It is the present indicative.

In French, the present tense can cover several ideas that English often separates:

• we wait
• we are waiting
• sometimes even a near-future idea, depending on context

So the French present tense is often broader than the English simple present.

In informal spoken French, people often use on instead of nous:

• On attend trente minutes.

This is extremely common in everyday speech.

So:

• Nous attendons trente minutes. = more formal or careful
• On attend trente minutes. = more natural in casual conversation

Both are correct.

A rough pronunciation is:

noo zah-tahn-dohn trahnt mee-newt

A few useful points:

• nous sounds like noo
• there is usually a liaison in nous attendons, so it sounds like noo-zattendons
• attendons has a nasal sound in the middle
• the final s in nous and minutes is silent
• the final e in trente is also silent

Sometimes, but it changes the feel a little.

• Nous attendons trente minutes. = We wait / are waiting for thirty minutes
• Nous attendons pendant trente minutes. = We wait for thirty minutes, with extra emphasis on the duration

Very often, French does not need pendant after attendre when a duration is given directly.

So the version without pendant is perfectly normal.