Ik kan het rustpunt niet bereiken, laat staan deze klimroute afmaken.

Laat staan is an idiomatic expression meaning something like:

• let alone
• much less

It introduces a second idea that is even less possible than the first one.

So in this sentence:

• Ik kan het rustpunt niet bereiken = I can’t reach the rest point
• laat staan deze klimroute afmaken = let alone finish this climbing route

The speaker is saying: if even the easier thing is impossible, the harder thing is certainly impossible too.

Dutch often uses laat staan in a shortened structure, just like English often says let alone finish this route instead of let alone that I could finish this route.

So laat staan deze klimroute afmaken is an elliptical structure: some words are understood and left out.

A fuller version could be:

• Ik kan het rustpunt niet bereiken, laat staan dat ik deze klimroute kan afmaken.

But the shorter version is very common and natural.

Because niet usually comes before the infinitive or verb phrase it negates when you have a modal verb like kunnen.

The structure is:

• Ik kan
  • rest of sentence + niet
    • infinitive

So:

• Ik kan het rustpunt niet bereiken.

This literally follows the Dutch pattern:

• subject: Ik
• finite verb: kan
• object: het rustpunt
• negation: niet
• infinitive: bereiken

Compare:

• Ik kan niet zwemmen.
• Ik kan hem niet helpen.
• Ik kan het rustpunt niet bereiken.

Because kan is a modal verb, from kunnen.

In Dutch, when you use a modal verb, the main verb usually stays in the infinitive at the end of the clause.

So:

• Ik kan bereiken = I can reach
• Ik kan afmaken = I can finish

In your sentence:

• kan is the conjugated verb
• bereiken and afmaken are infinitives

This is very normal Dutch word order.

Afmaken is a separable verb:

• base verb: maken
• separable prefix: af

When used as an infinitive, the parts stay together:

• afmaken

When used as a normal finite verb in a main clause, the prefix usually splits off:

• Ik maak de klimroute af.

But after a modal verb, you use the infinitive, so it stays together:

• Ik kan de klimroute afmaken.

That is why the sentence has afmaken, not maak af.

Yes, here afmaken means finish or complete.

It often suggests bringing something to its proper end.

Examples:

• Ik maak mijn huiswerk af. = I finish my homework.
• Zij maakten de tocht af. = They completed the trek.

Be aware that afmaken can also have other meanings in other contexts, including stronger ones like kill off or put an end to, but in this climbing sentence it simply means finish/complete.

Because rustpunt is a het-word in Dutch.

Dutch nouns take either:

• de
• het

Here the correct article is het, so:

• het rustpunt

You usually have to learn the article with the noun. There is not always a fully predictable rule, although diminutives always take het, and some noun classes tend to favor one article or the other.

Rustpunt literally means something like rest point, resting point, or point where you can pause and recover.

In a climbing or hiking context, it suggests a place where you can stop, rest, and regain energy before continuing.

So it is not just any point on the route; it is a meaningful stopping point.

Deze means this.

So:

• deze klimroute = this climbing route

Because klimroute is a de-word, Dutch uses deze for this.

Compare:

• deze route = this route
• dit boek = this book

So the choice between deze and dit depends on whether the noun is a de-word or a het-word.

Because Dutch, like English, often avoids repeating words that are obvious from context.

Compare English:

• I can’t reach the rest point, let alone finish this climbing route.

You do not have to say:

• I can’t reach the rest point, let alone I can finish this climbing route.

Dutch works similarly here. The modal idea I can’t is understood in the second part.

So:

• Ik kan het rustpunt niet bereiken, laat staan deze klimroute afmaken.

is shorter and more natural than repeating everything.

Yes, you can use a fuller laat staan dat... structure, but the exact wording has to fit the grammar and meaning.

For example:

• Ik kan het rustpunt niet bereiken, laat staan dat ik deze klimroute kan afmaken.

That is grammatical and clear.

Using laat staan dat ik deze klimroute afmaak is possible in some contexts, but because the first clause already uses kan, many learners will find it more parallel and natural to keep kan in the second clause too:

• ... laat staan dat ik deze klimroute kan afmaken.

The shorter version in your original sentence is the most compact and idiomatic one.

It is basically neutral Dutch.

Nothing in it is especially slangy or highly formal.
The expression laat staan is common and natural in both speech and writing.

The sentence sounds a bit vivid or expressive because it contrasts an easier goal with a harder one, but grammatically and stylistically it is normal standard Dutch.

Yes, very often.

Depending on context:

• het rustpunt bereiken can mean
  • reach the rest point
  • get to the rest point
  • make it to the rest point

In a physically demanding situation like climbing, make it to can sound especially natural in English, because it suggests effort and difficulty.

So the Dutch verb bereiken is straightforwardly reach, but in good English the best translation may vary a little with context.