En clase, mis compañeras y yo nos tuteamos, pero con la directora no.

Nos tuteamos means we use tú with each other.

The verb is tutear, which means to address someone as tú rather than using the more formal usted.
With nos, it becomes reciprocal here: we address each other informally.

So this is not just we speak; it specifically refers to the level of formality used when speaking.

The nos shows a reciprocal idea: we do this to each other.

Compare:

• Nos tuteamos = We use tú with each other
• Nos escribimos = We write to each other
• Nos vemos = We see each other

Without nos, tuteamos by itself would sound incomplete or would need an object, because tutear is normally something you do to someone.

In Spanish, it is more natural and polite to put yo after the other person or people:

• mis compañeras y yo
• mi hermano y yo
• Laura y yo

This is similar to the politeness rule in English where my classmates and I is preferred over I and my classmates.

Compañeras is the feminine plural form, so it tells us the classmates being referred to are female.

That suggests the speaker is talking about her female classmates and herself.

If the group were all male or mixed, Spanish would normally use compañeros.

So:

• mis compañeras y yo = my female classmates and I
• mis compañeros y yo = my classmates and I / my male classmates and I

It can mean in class, during class, or in the classroom context, depending on the situation.

Here, En clase sets the context: when we are in class / in class situations.

It does not necessarily focus only on the physical room. It can also mean in the class environment.

The comma separates the context-setting phrase from the main sentence.

• En clase, mis compañeras y yo nos tuteamos...

This is very natural in Spanish when a phrase like En clase, En casa, A veces, Por la mañana, etc. comes first and sets the scene.

The comma is not always absolutely required in short sentences, but it is very common and helps readability.

This is an example of ellipsis: Spanish often leaves out words that are understood from context.

Full version:

• En clase, mis compañeras y yo nos tuteamos, pero con la directora no nos tuteamos.

But Spanish prefers the shorter, more natural version:

• ...pero con la directora no.

The no stands for we do not do that with the headmistress/director.

In English, we do something similar:

• We use first names with our classmates, but not with the principal.

Because the idea is with the headmistress/headteacher/director, not to the headmistress.

The sentence contrasts how we speak with different people:

• nos tuteamos con mis compañeras
• no con la directora

Using con makes sense because the relationship is mutual or interpersonal: with each other / with someone.

You may also hear similar expressions like:

• Con mis amigos hablo de tú.
• Con mi jefe hablo de usted.

La directora is the feminine form of director.

In a school context in Spain, la directora usually means the headmistress, the principal, or the school director/headteacher, depending on the institution and the variety of English you prefer.

So the sentence contrasts informal speech with classmates and more formal speech with the person in authority.

Yes, especially in Spain. Tutear and related expressions are very common because the distinction between tú and usted is an important part of everyday Spanish.

You might hear:

• ¿Nos tuteamos? = Shall we use tú with each other?
• Puedes tutearme. = You can use tú with me.
• No me tutees. = Don’t address me as tú.

This is especially useful in Spain, where people often switch between tú and usted depending on age, formality, and social context.

Yes, but it would sound a little different.

For example:

• En clase, mis compañeras y yo nos tuteamos, pero a la directora la tratamos de usted.

This version makes the contrast fully explicit:

• with classmates = tú
• with the headmistress = usted

The original sentence is shorter and more natural because no already implies we do not use tú with her.

Here, no works as a short negative answer to the idea already mentioned.

The structure is:

• X, pero con Y no.

Meaning:

• We do X, but not with Y.

Examples:

• Con mis amigos salgo mucho, pero con mis vecinos no.
• En casa hablamos español, pero en el trabajo no.

So no at the end is completely natural and refers back to the verb phrase already introduced: nos tuteamos.

Yes, it is similar, but nos tuteamos is more concise and idiomatic.

Possible alternatives:

• Nos tuteamos.
• Nos tratamos de tú.
• Hablamos de tú. (less common in this exact structure)

All of them relate to using tú rather than usted, but tutear is the most direct verb for that idea.