Ons bereik nie vleilande nie, laat staan nog broeigebiede.

Afrikaans normally uses double negation in standard negative statements.

So:

• Ons bereik vleilande. = We reach wetlands.
• Ons bereik nie vleilande nie. = We do not reach wetlands.

The first nie usually comes after the verb or the part being negated, and the second nie usually comes near the end of the clause.

In this sentence:

• Ons bereik nie vleilande nie = We don’t reach wetlands

This is one of the most important sentence patterns in Afrikaans.

Laat staan nog is an idiomatic expression meaning something like:

• let alone
• much less
• never mind

So the sentence means:

• We do not even reach wetlands, let alone breeding areas.

It introduces something that is even less likely, harder, more extreme, or further out of reach than what came before.

Because the verb is understood from the first part of the sentence.

The full idea is:

• Ons bereik nie vleilande nie, laat staan nog broeigebiede.
• literally: We don’t reach wetlands, let alone breeding areas.

Afrikaans, like English, often leaves out repeated material when it is obvious. English does the same:

• We can’t afford a car, let alone a house.

You do not need to repeat can’t afford in the second part.

So here, bereik is understood in the second part:

• laat staan nog broeigebiede = let alone reach breeding areas

In this expression, nog helps strengthen the idea of even less so / much less / let alone.

On its own, nog often means things like:

• still
• yet
• another / more

But in laat staan nog, it is part of the fixed idiomatic phrase. It is best learned as a whole expression rather than translated word by word.

Yes, bereik often means reach, and it can be used in both physical and abstract senses.

Examples:

• Ons bereik die dorp. = We reach the town.
• Hy bereik sy doel. = He achieves/reaches his goal.

In your sentence, bereik suggests getting to, reaching, or extending to wetlands and breeding areas, depending on context.

They are plural nouns:

• vleiland = wetland

• vleilande = wetlands

• broeigebied = breeding area / breeding ground
• broeigebiede = breeding areas / breeding grounds

Afrikaans often uses the plural in a general sense, just like English:

• Wetlands are important.
• Breeding areas are protected.

So here the sentence is speaking generally, not about one specific wetland or one specific breeding area.

Because the sentence is talking about these places in general, not about specific ones already identified.

Compare:

• Ons bereik nie vleilande nie. = We do not reach wetlands.
  general category

• Ons bereik nie die vleilande nie. = We do not reach the wetlands.
  specific wetlands

The version without die is natural when speaking broadly or categorically.

It is a compound noun, which is very common in Afrikaans.

It is made from:

• broei = breed / hatch / incubate
• gebied = area / region

So:

• broeigebied = breeding area
• broeigebiede = breeding areas

Afrikaans forms many nouns this way, by combining parts into one word.

It is a real, natural Afrikaans expression, and it is fairly common in writing and speech.

It can sound a bit emphatic or rhetorical, much like English let alone or much less.

Examples:

• Hy kan skaars loop, laat staan nog hardloop.
  He can hardly walk, let alone run.

• Ons het nie tyd vir tee nie, laat staan nog vir aandete.
  We don’t have time for tea, let alone dinner.

So the structure in your sentence is very normal.

Not really. A word-for-word translation would not sound natural in English.

It is better to treat it as an idiom meaning:

• let alone
• much less
• never mind

That is often the best approach with fixed expressions in Afrikaans: learn the whole phrase as one unit rather than trying to map each word directly.

It has two parts:

1. Ons bereik nie vleilande nie
   a complete negative clause: We do not reach wetlands

2. laat staan nog broeigebiede
   an idiomatic follow-up meaning: let alone breeding areas

So the sentence works like this:

• statement of something already not achieved
• followed by something even more out of reach

That gives it a strong sense of escalation:

• not even X, much less Y