Gebruik sowel die bevestigingsplaat as die hoekbeugel.

Sowel ... as means both ... and.

So:

• sowel die bevestigingsplaat as die hoekbeugel
  = both the mounting plate and the angle bracket

It is a paired structure. Sowel introduces the first item, and as introduces the second one.

A simple comparison:

• die bevestigingsplaat en die hoekbeugel = the mounting plate and the angle bracket
• sowel die bevestigingsplaat as die hoekbeugel = both the mounting plate and the angle bracket

The version with sowel ... as gives a clearer sense that you should use the two items together.

Afrikaans normally repeats the article before each noun here, just as English does in both the plate and the bracket.

So:

• die bevestigingsplaat
• die hoekbeugel

and together:

• sowel die bevestigingsplaat as die hoekbeugel

This is completely normal. Repeating die makes it clear that there are two separate noun phrases being linked.

Yes. Gebruik is being used as an imperative, so the sentence is an instruction:

• Gebruik ... = Use ...

This is very common in manuals, labels, and instructions.

In Afrikaans, the imperative often looks the same as the basic verb form:

• gebruik = use
• Gebruik dit. = Use it.

The subject is not stated, but the meaning is understood as you.

Because this is a command.

In Afrikaans imperatives, the verb usually comes first:

• Gebruik die skroef. = Use the screw.
• Maak die deur toe. = Close the door.

So in your sentence:

• Gebruik
  • the thing(s) to be used

If it were a normal statement, you would usually include a subject:

• Jy gebruik sowel die bevestigingsplaat as die hoekbeugel.
  = You use both the mounting plate and the angle bracket.

They are compound nouns, which are very common in Afrikaans.

Afrikaans often joins shorter words together into one longer noun.

bevestigingsplaat

This can be understood as something like:

• bevestiging = fastening / mounting / attachment
• plaat = plate

So bevestigingsplaat means a mounting plate or fastening plate, depending on context.

hoekbeugel

This can be understood as:

• hoek = angle / corner
• beugel = bracket / support

So hoekbeugel means an angle bracket or corner bracket.

This compounding pattern is extremely common in Afrikaans technical vocabulary.

Because as is part of the fixed expression sowel ... as.

You should think of it as a set pattern:

• sowel X as Y = both X and Y

So in this sentence:

• sowel die bevestigingsplaat as die hoekbeugel

If you used en instead, you would no longer have that exact both ... and structure.

Compare:

• Gebruik die bevestigingsplaat en die hoekbeugel.
  = Use the mounting plate and the angle bracket.
• Gebruik sowel die bevestigingsplaat as die hoekbeugel.
  = Use both the mounting plate and the angle bracket.

The second version stresses that both items are to be used.

Yes, but the meaning changes slightly.

Without sowel ... as, you just get a plain and:

• Gebruik die bevestigingsplaat en die hoekbeugel.

That still makes sense, but it is a little less emphatic. It simply joins the two objects.

With sowel ... as, the sentence more clearly highlights that both items are required.

So:

• en = and
• sowel ... as = both ... and

Yes. Here die means the.

One useful thing for English speakers is that Afrikaans does not change the definite article for gender:

• die plaat = the plate
• die beugel = the bracket

Unlike languages such as German or Dutch, Afrikaans uses die as the normal definite article for singular nouns and also for plural nouns in many cases.

So learners often find die simpler than articles in some other languages.

A very literal breakdown would be:

• Gebruik = Use
• sowel = both
• die bevestigingsplaat = the mounting plate
• as = and
• die hoekbeugel = the angle bracket

So the structure is roughly:

• Use both the mounting plate and the angle bracket.

That is already quite close to normal English, which makes this sentence relatively straightforward once you know the pattern sowel ... as.