Nos encordamos y revisamos el arnés.

Here encordamos comes from encordarse, a climbing verb meaning to rope up or to tie in with the rope.

So Nos encordamos means something like:

• We roped up
• We tied ourselves in
• We got attached to the rope

In everyday Spanish outside climbing, encordarse is not very common. In this sentence, it is clearly climbing vocabulary.

Nos is the reflexive pronoun for we.

With encordarse, the reflexive form is the normal one when people are attaching themselves to the rope:

• me encuerdo = I rope up
• te encuerdas = you rope up
• se encuerda = he/she ropes up
• nos encordamos = we rope up

So nos shows that the action is being done by the people to themselves, or that they are getting themselves connected to the rope.

In climbing contexts, it can also feel a bit reciprocal: the group is roping up together.

It can be either one, because for nosotros verbs ending in -ar, the present and preterite forms are often identical.

So:

• nos encordamos can mean we rope up / we are roping up
• nos encordamos can also mean we roped up

The same is true for revisamos:

• we check
• we checked

You need context to know which one it is.

For example:

• Antes de cada subida, nos encordamos y revisamos el arnés.
  = present / habitual

• Llegamos a la base, nos encordamos y revisamos el arnés.
  = past

Because revisar here is being used as a normal, non-reflexive verb: to check / inspect.

• Nos encordamos = reflexive verb
• revisamos el arnés = normal transitive verb with a direct object

So the structure is:

• nos encordamos = we roped up
• revisamos el arnés = we checked the harness

If you said nos revisamos, that would mean we checked ourselves or we examined ourselves, which is a different idea.

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

Here, encordamos and revisamos already show we because of the -amos ending.

So:

• Nosotros nos encordamos y revisamos el arnés
• Nos encordamos y revisamos el arnés

Both are grammatical, but the second is more natural unless you want emphasis or contrast.

Spanish often uses the definite article (el, la, los, las) where English would use a possessive like my, your, our, especially when ownership is obvious from context.

So in context, revisamos el arnés can naturally mean:

• we checked the harness
• or we checked our harness

Spanish does this a lot with body parts, clothing, and equipment when it is clear whose thing is being talked about.

Using nuestro arnés is possible, but it adds emphasis to ownership and often sounds less natural if the context already makes it obvious.

This depends on the context.

El arnés could mean:

• one specific harness
• the harness as a piece of equipment in a general sense
• each person’s harness, if the context makes that interpretation clear

In very literal terms, if two or more people are each checking their own harnesses, Spanish might also say los arneses. So the singular here is not the only possible wording.

A learner should understand that Spanish sometimes uses the singular for something understood generically or contextually, but in another situation you might indeed hear:

• Nos encordamos y revisamos los arneses.

Arnés is a masculine noun:

• el arnés = the harness

Its written accent is important because it shows the stress falls on the last syllable: ar-NÉS.

The plural is:

• los arneses

Notice that the accent disappears in the plural because the stress pattern changes naturally:

• arnés
• arneses

In climbing, yes. Encordarse is a specialized and very natural verb for this situation.

Compare:

• encordarse = to rope up / tie in
• atarse a la cuerda = to tie oneself to the rope

The second one is understandable, but it sounds more literal and less like standard climbing vocabulary. If you are talking about climbing in Spanish, encordarse is the better choice.

You can, but it may sound less natural in English.

A very literal version would be:

• We roped ourselves up and checked the harness.

A more natural English translation might be:

• We roped up and checked the harness.
• We tied in and checked the harness.

So this is a good example of where understanding the Spanish structure is useful, but a word-for-word translation is not always the best final English version.