Ons bekyk nie soseer deurkosyne nie, maar vals bodems.

It is a very common contrast pattern meaning not so much X, but Y or not so much X as Y.

So in this sentence, the speaker is not saying doorframes are impossible or completely irrelevant. The idea is more:

• X is not the best way to describe what we are looking at
• Y is the better or more important description

So Ons bekyk nie soseer deurkosyne nie, maar vals bodems means something like We are looking not so much at doorframes, but at false bottoms.

Afrikaans normally uses a double negative structure: nie ... nie.

In this sentence:

• the first nie starts the negation
• the second nie closes it

Here the negated part is the not so much doorframes idea:

• nie soseer deurkosyne nie

Then maar vals bodems gives the correction or contrast.

So the pattern is:

• nie
  • the part being downplayed + nie, maar
    • the preferred alternative

This is normal Afrikaans grammar, even though it feels unusual to English speakers.

In this structure, soseer means something like so much, particularly, or really.

By itself, it is not always translated word-for-word in English. In nie soseer ... nie, maar ..., it helps create the meaning not so much X, but Y.

So you should learn nie soseer ... nie, maar ... as a useful chunk, not just as separate words.

Bekyk is a verb meaning look at, view, or inspect/examine.

The important difference is:

• bekyk takes a direct object
• kyk usually needs na when it means look at

So:

• Ons bekyk deurkosyne = We examine/look at doorframes
• Ons kyk na deurkosyne = We look at doorframes

Bekyk often sounds a bit more deliberate or analytical than kyk na. It suggests you are examining something rather than just glancing at it.

Because bekyk is a transitive verb. It directly takes its object.

So Afrikaans says:

• Ons bekyk deurkosyne
• not Ons bekyk na deurkosyne

If the verb were kyk, then you would normally need na:

• Ons kyk na deurkosyne

This is a good example of how different Afrikaans verbs govern their objects differently.

It is the simple present, but in Afrikaans the simple present often covers meanings that English expresses with both:

• we look
• we are looking

So Ons bekyk ... can mean either, depending on context.

English uses the progressive much more often than Afrikaans does. That is why a plain present form in Afrikaans can sound like a present continuous in English.

Because Afrikaans writes compound nouns as one word.

Deurkosyn is made from:

• deur = door
• kosyn = frame/jamb

Together they form one noun: deurkosyn.

Its plural is deurkosyne.

This is very typical of Afrikaans and also of Dutch and Germanic compounding more generally. English often writes the equivalent as two words, but Afrikaans strongly prefers one-word compounds.

Because Afrikaans, like English, can use bare plurals to talk about things in a general or category-like way.

Compare English:

• We are looking at doorframes, not false bottoms
• no the is needed if you mean the categories generally

The Afrikaans sentence does the same thing:

• deurkosyne
• vals bodems

If you added die, it would sound more definite, as if you meant particular doorframes or particular false bottoms already known from context.

Because they are built differently:

• deurkosyne is a compound noun → written as one word
• vals bodems is an adjective + noun combination → normally written as two words

So:

• deur
  • kosyn → deurkosyn
• vals
  • bodems stays separate, because vals describes the noun

A small extra note: many learners will expect valse bodems in careful standard Afrikaans, because adjectives before nouns often take an -e form. That is the safer form for a learner to produce. If you see vals bodems, understand it as the same basic idea.

It means but, but in this sentence it is closer to but rather or but instead.

After nie soseer ... nie, maar introduces the better or more accurate alternative.

So the logic is:

• not so much X
• but rather Y

That is why maar is an important part of the contrast in this sentence.