Nous nous échauffons puis nous nous encordons.

Because the sentence contains two different nous words:

• the first nous = the subject pronoun: we
• the second nous = the reflexive pronoun: ourselves

So:

• Nous nous échauffons = We warm ourselves up
• Nous nous encordons = We rope ourselves up / We tie ourselves onto a rope

This is very common with French reflexive verbs. English sometimes uses -self/-selves, but French uses a reflexive pronoun before the verb.

They are reflexive (or pronominal) verbs.

Their dictionary forms are:

• s’échauffer = to warm up
• s’encorder = to rope up / tie oneself to a rope

The se / s’ is part of the verb’s usual form. When you conjugate it, se changes to match the subject:

• je me
• tu te
• il/elle se
• nous nous
• vous vous
• ils/elles se

So:

• nous nous échauffons
• nous nous encordons

Because in French, object pronouns — including reflexive pronouns — normally come before the conjugated verb.

So French says:

• Nous nous échauffons
• literally: We ourselves warm up

That feels backwards to an English speaker, because English usually puts ourselves after the verb:

• We warm ourselves up

This word order is normal in French and applies to many pronouns, not just reflexive ones.

Here, puis means then or next.

So the sentence structure is:

• Nous nous échauffons = We warm up
• puis = then
• nous nous encordons = we rope up

Yes, it is related to et puis, which can also mean and then.
In this sentence, puis alone is enough and sounds natural.

Because they are conjugated for nous in the present tense.

Both verbs are regular -er verbs:

• échauffer
• encorder

For regular -er verbs in the present tense, the nous form ends in -ons:

• nous échauffons
• nous encordons

Since these are reflexive verbs, you add the reflexive pronoun too:

• nous nous échauffons
• nous nous encordons

Yes. Grammatically, it is in the present tense.

French often uses the present tense to describe:

• what people generally do
• what is happening now
• steps in a routine or sequence

So this can mean something like:

• We warm up, then we rope up
• First we warm up, then we tie onto the rope

Even though it is present tense, it can still describe a natural order of actions.

It can look strange, but it is completely normal.

Both nous are pronounced the same way, so nous nous is basically said twice in a row. In normal speech, the phrase flows as part of the whole sentence.

A learner may feel it is repetitive, but French speakers are very used to this pattern:

• nous nous levons
• nous nous appelons
• nous nous reposons
• nous nous échauffons

So yes, it is a little visually unusual, but not unnatural at all.

Because the verb must agree with the subject nous.

The subject is we, so the verb needs the nous form:

• j’échauffe
• tu échauffes
• il/elle échauffe
• nous échauffons
• vous échauffez
• ils/elles échauffent

So nous nous échauffons is the correct form.

The same idea applies to encordons:

• nous nous encordons

S’encorder is a more specialized verb, often used in climbing, mountaineering, or similar contexts.

It means to tie oneself to a rope, often as part of a climbing team. So nous nous encordons suggests:

• we put on and attach the rope
• we rope up together
• we tie ourselves in before climbing

It is not as everyday as verbs like se lever or s’habiller, but it is perfectly natural in the right context.

No, not in standard French.

Because s’échauffer and s’encorder are being used reflexively here, the reflexive pronoun is required:

• Nous nous échauffons
• Nous nous encordons

If you removed the second nous, the sentence would be ungrammatical.

The reflexive pronoun is an essential part of the construction.

Not always.

Sometimes it does translate directly:

• nous nous regardons = we look at ourselves

But often English uses a simpler verb without ourselves:

• nous nous échauffons = we warm up
• not necessarily we warm ourselves up, unless you want to emphasize the reflexive idea

So the French reflexive form does not always require an explicit self/selves in natural English. It depends on how English normally expresses the idea.