Podemos sentarnos atrás si quieres.

Podemos is the we form of poder, which means to be able to / can.

• puedo = I can
• puedes = you can
• puede = he/she/it can
• podemos = we can
• podéis = you all can (informal plural in Spain)
• pueden = they/you all can

So Podemos sentarnos atrás means We can sit in the back.

In context, podemos can also sound like a suggestion in English, similar to we can or we could.

Because the verb here is sentarse, not just sentar.

• sentar usually means to seat someone / to place someone in a sitting position
• sentarse means to sit down / to sit oneself

So:

• Vamos a sentar al niño. = We are going to seat the child.
• Vamos a sentarnos. = We are going to sit down.

In sentarnos, the ending -nos means ourselves / us, so literally it is something like to seat ourselves, which is how Spanish expresses to sit down.

In Spanish, object and reflexive pronouns can be attached to an infinitive.

So these are both possible:

• Podemos sentarnos atrás.
• Nos podemos sentar atrás.

Both mean the same thing: We can sit in the back.

Attaching the pronoun to the infinitive is very common and completely natural.

Usually, no major difference in meaning. Both are natural.

The main difference is style and rhythm:

• Podemos sentarnos atrás sounds very smooth and neutral.
• Nos podemos sentar atrás is also correct, but puts the reflexive pronoun before the conjugated verb.

Spanish often allows both placements when there is a conjugated verb + infinitive.

Here atrás means in the back / at the back / in the rear.

In this sentence, it most likely refers to a place like:

• the back seats of a car
• the back of a room
• the rear part of a place

So sentarnos atrás means sit in the back.

This is a very common question.

• atrás usually means back / behind / in the back
• detrás usually means behind, often relative to something else

So:

• Podemos sentarnos atrás. = We can sit in the back.
• Está detrás de la puerta. = It is behind the door.

A useful way to think about it:

• atrás often refers to a general rear position
• detrás de usually means behind a specific object or person

In this sentence, the idea is simply at the back, so atrás fits well.

Because atrás can work on its own as an adverb of place.

Spanish often says:

• adelante = in front / forward
• atrás = behind / in the back
• arriba = up / upstairs
• abajo = down / downstairs

So sentarnos atrás is perfectly normal and does not need en.

English often needs a preposition like in or at, but Spanish does not always.

Si quieres means if you want.

It is made of:

• si = if
• quieres = you want

So the full sentence means something like:

• We can sit in the back if you want.

This makes the sentence sound polite and flexible, as if the speaker is leaving the choice to the other person.

Because quieres is the tú form of querer.

• quiero = I want
• quieres = you want (informal singular)
• quiere = he/she/you want (formal singular)
• queremos = we want
• queréis = you all want (informal plural in Spain)
• quieren = they/you all want

So si quieres is talking to one person informally.

If you were speaking more formally, you would say:

• Podemos sentarnos atrás si quiere.

If you were speaking to more than one person in Spain:

• Podemos sentarnos atrás si queréis.

Because Spanish often leaves out subject pronouns when the verb already makes the subject clear.

• Podemos already tells you it means we can
• Quieres already tells you it means you want (informal singular)

So Spanish usually says:

• Podemos sentarnos atrás si quieres.

Not usually:

• Nosotros podemos sentarnos atrás si tú quieres.

The longer version is possible, but it would normally be used only for emphasis, contrast, or clarity.

Literally, podemos means we can. But in real conversation, it can also function like a suggestion, which in English might sound like we could.

So depending on tone and context, this sentence could feel like:

• We can sit in the back if you want.
• We could sit in the back if you want.

Spanish often uses the present tense in places where English might choose could for a softer suggestion.

Yes, absolutely.

• Podemos sentarnos atrás si quieres.
• Si quieres, podemos sentarnos atrás.

Both are correct. The meaning is the same.

The difference is just emphasis:

• Podemos sentarnos atrás si quieres starts with the suggestion
• Si quieres, podemos sentarnos atrás starts with the condition or politeness part

With sentarnos from sentarse, the idea is normally to sit down / to seat ourselves.

In many everyday contexts, though, English may simply say sit:

• We can sit in the back if you want.

So in practice, it can refer to taking seats in the back, even if the underlying Spanish verb is the reflexive sentarse.