Laura y yo hablamos al mismo tiempo, y la profesora nos pide calma.

Because Laura y yo means Laura and I, and any subject that includes yo takes the first person plural form, equivalent to nosotros/nosotras.

So:

• yo hablo = I speak
• Laura y yo hablamos = Laura and I speak
• ellos hablan = they speak

Even though there are two people, one of them is I, so Spanish uses we, not they.

Yes. Since Laura and the speaker are both female, Laura y yo could be replaced by nosotras.

So this would also work:

• Nosotras hablamos al mismo tiempo.

If the group were mixed or the gender were unknown, Spanish would normally use nosotros.

It can mean either, depending on context.

For regular -ar verbs, the present and the preterite forms for nosotros/nosotras are often identical:

• hablamos = we speak / we are speaking
• hablamos = we spoke

In this sentence, the rest of the context makes it clear that it is present:

• la profesora nos pide calma is also in the present
• the situation sounds like something happening now

So here, hablamos means we speak or more naturally we’re talking.

Al mismo tiempo means at the same time.

Here:

• al = contraction of a + el
• mismo = same
• tiempo = time

So literally it is something like at the same time.

This is a very common fixed expression in Spanish:

• Hablan al mismo tiempo. = They speak at the same time.

Because the sentence joins two full clauses:

• Laura y yo hablamos al mismo tiempo
• la profesora nos pide calma

In Spanish, a comma before y is sometimes used when:

• the clauses are longer
• there is a change of subject
• the writer wants a clearer pause

Here, the subject changes from Laura y yo to la profesora, so the comma sounds natural.

Because profesora is the feminine form of profesor, meaning teacher.

• el profesor = the male teacher
• la profesora = the female teacher

The article must match the noun:

• la profesora
• el profesor

So this sentence tells us the teacher is female.

Nos means to us or us.

The verb pedir often works like this:

• pedir algo a alguien = to ask someone for something

So:

• La profesora nos pide calma literally means
• The teacher asks us for calm

In natural English, that often becomes:

• The teacher asks us to be calm
• The teacher tells us to calm down

Here nos is an object pronoun placed before the conjugated verb pide.

Because the subject of that verb is la profesora, which is singular.

So:

• la profesora pide = the teacher asks
• las profesoras piden = the teachers ask

The fact that nos refers to more than one person does not change the verb. The verb agrees with the subject, not with the object pronoun.

Spanish often uses a noun where English prefers a verb phrase.

• pedir calma literally = to ask for calm
• natural English = to ask people to calm down

This is a normal and idiomatic Spanish expression. Similar examples are:

• pedir silencio = ask for silence
• pedir paciencia = ask for patience

So nos pide calma is a very natural way to express the idea.

Because abstract nouns like calma, silencio, or paciencia often appear without an article after verbs like pedir.

So Spanish commonly says:

• pedir calma
• pedir silencio
• tener paciencia

Using la calma would usually sound more specific or less natural in this structure. Here the idea is general: the teacher is asking for calmness.

Yes, that is possible, but it changes the feel slightly.

• hablamos al mismo tiempo = we speak / we are talking at the same time
• estamos hablando al mismo tiempo = we are speaking at the same time, with stronger emphasis on the action happening right now

In many everyday situations, Spanish prefers the simple present where English might use the present continuous. So hablamos is perfectly natural here.

It is the most common and straightforward expression in sentences like this.

For example:

• Los dos hablaron al mismo tiempo.
• No podemos hablar todos al mismo tiempo.

There are other ways to express similar ideas depending on context, but al mismo tiempo is the standard phrase learners should know first.