No sabemos adónde ir.

In Spanish, standard negation usually puts no directly before the conjugated verb.

• Sabemos = we know
• No sabemos = we do not know / we don’t know

So:

• No sabemos adónde ir = We don’t know where to go

Sabemos is the 1st person plural present tense of saber.

• saber = to know
• sabemos = we know

The subject nosotros (we) is not stated because Spanish often leaves subject pronouns out when the verb ending already shows who the subject is.

So (Nosotros) no sabemos... and No sabemos... mean the same thing.

Spanish has more than one verb for to know.

• saber is used for knowing information, facts, or how to do something
• conocer is used for being familiar with people, places, or things

In No sabemos adónde ir, the idea is we don’t know the answer to the question “where should we go?” That is why saber is the correct verb.

Because after saber in this kind of structure, Spanish often uses an indirect question plus an infinitive.

• No sabemos adónde ir = We don’t know where to go

Literally, it is something like:

• We don’t know where to go

The action ir is not conjugated because sabemos is already the main conjugated verb in the sentence.

This pattern is very common:

• No sé qué hacer = I don’t know what to do
• No sabemos cuándo salir = We don’t know when to leave

Adónde is used when the idea is destination or movement toward a place.

Since ir means to go, it naturally involves movement, so adónde is very appropriate:

• adónde ir = where to go

By contrast, dónde is more about location:

• dónde está = where it is

That said, in everyday Spanish, many speakers also say dónde ir, especially in less formal speech. But adónde is especially clear and traditional here because it matches the idea of motion.

The a adds the idea of to or toward.

So:

• dónde = where
• adónde = to where / where to

In English, we usually just say where, but Spanish can show the direction more explicitly.

With verbs of movement, this is common:

• ¿Adónde vas? = Where are you going?
• No sabemos adónde ir = We don’t know where to go

Yes, you may see both adónde and a dónde.

In many cases, both are accepted, and the difference is often more about spelling preference or style than meaning.

So these are both possible:

• No sabemos adónde ir
• No sabemos a dónde ir

The one-word form adónde is very common and looks especially neat in standard writing. The two-word form is also widely used.

Because it is an interrogative/exclamative word used in a question or an indirect question.

Spanish gives an accent to words like:

• qué
• quién
• cuándo
• dónde
• adónde
• cómo

Even though this sentence is not a direct question, it contains an indirect question:

• No sabemos adónde ir = We don’t know where to go

So adónde keeps the written accent.

Compare:

• No sé dónde está = indirect question, so dónde
• El lugar donde vivo = relative word, so donde without accent

Not as a full sentence, no. It is a statement.

But inside it, adónde ir functions as an indirect question:

• No sabemos adónde ir

It is like saying:

• We don’t know: “Where should we go?”

So the whole sentence is not written with question marks, but it still contains a question idea.

Because after verbs like saber, Spanish directly introduces the indirect question with the question word.

So you say:

• No sabemos adónde ir
• No sé qué hacer
• No sabemos cuándo salir

Not:

• No sabemos que adónde ir

In this structure, que is not used.

Yes, many native speakers do say No sabemos dónde ir, and it is very common.

The difference is mainly this:

• dónde focuses on where
• adónde highlights destination / where to

Because ir is a verb of movement, adónde is especially precise. But dónde is also widely used in real Spanish.

So:

• No sabemos adónde ir = a bit more explicitly where to go
• No sabemos dónde ir = also very natural in everyday use

No, that is completely correct.

Spanish often omits subject pronouns because the verb ending already shows the subject:

• sabemos = we know

So the usual version is simply:

• No sabemos adónde ir

But you can add nosotros if you want to emphasize we:

• Nosotros no sabemos adónde ir

This can sound like:

• We don’t know where to go
  perhaps contrasting with someone else who does know.