Die plafon bly skoon deurdat ons die rand afplak.

Here bly means stays or remains.

So Die plafon bly skoon means The ceiling stays clean / The ceiling remains clean.

This is a very common use of bly in Afrikaans:

• bly stil = stay quiet
• bly kalm = stay calm
• bly oop = stay open

It does not mean to stay somewhere in this sentence.

Yes. Afrikaans uses die as the definite article for almost everything:

• die man = the man
• die vrou = the woman
• die huis = the house
• die kinders = the children

Unlike English, there is no distinction like the for singular vs plural, and unlike languages such as German or Dutch, Afrikaans does not change the article for grammatical gender in this way.

So both die plafon and die rand simply mean the ceiling and the edge.

Deurdat means something like because, by the fact that, or by means of the fact that.

In this sentence, it introduces the reason or method:

• Die plafon bly skoon deurdat ons die rand afplak.
• The ceiling stays clean because / by taping off the edge.

In everyday English, you would usually translate it naturally rather than word-for-word.

A useful idea:

• omdat = because
• deurdat = because, through the fact that, by doing so

In many practical contexts like this one, deurdat can suggest the mechanism by which something happens.

Because afplak is a separable verb.

The full verb is afplak, meaning to tape off, to seal off with tape, or to mask off.

In Afrikaans:

• In a main clause, separable verbs often split:
  • Ons plak die rand af.
• In an infinitive or subordinate clause, they usually stay together:
  • ... dat ons die rand afplak.

So in your sentence:

• deurdat ons die rand afplak

the verb appears at the end of the clause and stays together as afplak.

Because deurdat introduces a subordinate clause, and in Afrikaans, subordinate clauses usually send the finite verb to the end.

Compare:

Main clause

• Ons plak die rand af.
• We tape off the edge.

Subordinate clause

• ... deurdat ons die rand afplak
• ... because we tape off the edge

So the pattern is:

• conjunction + subject + object + verb

This is very common after words like:

• dat = that
• omdat = because
• terwyl = while
• as = if/when
• deurdat = because / through the fact that

Because in this subordinate clause, the object comes before the verb.

Afrikaans subordinate clause order is typically:

• conjunction
• subject
• object(s)
• verb(s)

So:

• deurdat = conjunction
• ons = subject
• die rand = object
• afplak = verb

That gives:

• deurdat ons die rand afplak

Putting afplak before die rand would sound wrong in standard Afrikaans.

Rand means edge, rim, or border.

In this sentence, it probably refers to the edge where the ceiling meets the wall, especially in a painting or decorating context.

So die rand afplak suggests:

• taping off the edge
• masking the edge with tape

This is the kind of thing you do to keep paint from getting onto the ceiling.

Usually, yes.

Afplak commonly means:

• to tape something off
• to mask something with tape
• to seal or cover an area using tape

In a painting context, die rand afplak strongly suggests using masking tape to protect the edge.

So this is more specific than just covering something. It usually involves adhesive tape.

Afrikaans often uses the simple present where English might use the present continuous.

So:

• ons plak die rand af can mean we tape off the edge or we are taping off the edge, depending on context.

Afrikaans does have ways to emphasize an ongoing action, for example:

• Ons is besig om die rand af te plak.
• We are busy taping off the edge.

But in many normal sentences, the simple present is enough.

Yes, in many contexts you could say:

• Die plafon bly skoon omdat ons die rand afplak.

That would mean:

• The ceiling stays clean because we tape off the edge.

The difference is subtle:

• omdat is the more general word for because
• deurdat can sound a bit more like through the fact that or by doing this

In this sentence, deurdat highlights the method or means by which the ceiling stays clean.

Yes:

• Deurdat ons die rand afplak, bly die plafon skoon.

This is perfectly natural.

Notice what happens in the main clause after the introductory subordinate clause:

• bly comes before die plafon

That is because Afrikaans, like Dutch and German, normally keeps the finite verb in the second position in a main clause.

So:

• Die plafon bly skoon ... but
• Deurdat ons die rand afplak, bly die plafon skoon.

Skoon is an adjective, and here it means clean.

In:

• Die plafon bly skoon

it functions like a predicative adjective, just like in English:

• The ceiling stays clean

More examples:

• Die vloer is skoon. = The floor is clean.
• Hou dit skoon. = Keep it clean.
• Die vensters bly skoon. = The windows stay clean.

Yes. Plafon is the standard word for ceiling.

So:

• die plafon = the ceiling

It is a common everyday word, especially in household, building, and decorating contexts.

Yes, exactly.

If you turn the subordinate clause into an independent sentence, you get:

• Ons plak die rand af.

This is useful because it shows how separable verbs behave:

Main clause

• Ons plak die rand af.

Subordinate clause

• ... dat ons die rand afplak.

That alternation is something learners of Afrikaans see very often.