Sy wonder of die kelner nog warm brood sal bedien.

No. In this sentence, of means whether or sometimes if in an indirect-question sense.

So Sy wonder of ... means She wonders whether ...

This is a very common point for English speakers, because Afrikaans of is often a false friend. It usually does not mean English of.

Examples:

• Ek weet nie of hy kom nie. = I don’t know whether he is coming.
• Sy vra of jy reg is. = She asks whether you are okay.

Afrikaans verbs do not change the way English verbs do for different subjects.

In English:

• I wonder
• she wonders

In Afrikaans, the verb usually stays the same:

• Ek wonder
• Sy wonder
• Hulle wonder

So wonder is correct with sy.

Because after of introducing a subordinate clause, Afrikaans usually sends the verb cluster to the end.

Main clause:

• Die kelner sal nog warm brood bedien.

Subordinate clause after of:

• ... of die kelner nog warm brood sal bedien.

This is one of the biggest word-order patterns in Afrikaans:

• main clause: finite verb tends to come early
• subordinate clause: verbs move toward the end

Compare:

• Hy sê dat sy môre kom.
• Ek weet of hulle dit sal doen.

Sal is the future auxiliary, meaning will.

Bedien means serve.

So:

• sal bedien = will serve

Afrikaans often forms the future with sal + infinitive, similar to English will + verb.

Examples:

• Ek sal gaan. = I will go.
• Hulle sal wag. = They will wait.
• Die kelner sal brood bedien. = The waiter will serve bread.

Here nog means something like still, yet, or again, depending on context.

In this sentence, it most likely suggests:

• still serving warm bread or
• serving warm bread again / any more

Because the meaning is context-dependent, nog is a flexible word in Afrikaans.

Common uses:

• Ek is nog hier. = I am still here.
• Wil jy nog koffie hê? = Do you still want coffee? / Do you want more coffee?
• Is daar nog brood? = Is there still bread left?

So in your sentence, nog warm brood adds the idea of continued availability or continuation.

In Afrikaans, adjectives before nouns can appear in different forms, but many common adjective uses are much simpler than in languages with lots of agreement.

Here warm brood means warm bread, and warm stays in its basic form.

You do not need to make it agree for gender, because Afrikaans nouns do not have grammatical gender like, for example, German.

So:

• warm brood = warm bread
• warm sop = warm soup
• warm koffie = warm coffee

Yes. Die here means the.

Afrikaans uses:

• die = the
• ’n = a / an

So:

• die kelner = the waiter
• ’n kelner = a waiter

Unlike English, Afrikaans uses the same definite article die for all nouns:

• die man = the man
• die vrou = the woman
• die brood = the bread

Traditionally, kelner often corresponds to waiter, but in real usage it can sometimes be used more generally depending on context. If a learner wants a straightforward translation, kelner is usually best understood as waiter.

Related word:

• kelnerin = waitress

But many learners will simply meet kelner as the standard restaurant-service word and understand it from context.

After sal, Afrikaans uses the bare infinitive, without a separate to.

So:

• sal bedien = will serve not will to serve

This is similar to English modal verbs:

• will serve
• can serve
• must serve

Afrikaans works similarly:

• sal bedien = will serve
• kan bedien = can serve
• moet bedien = must serve

The given sentence is the normal and natural structure for this meaning.

Standard form:

• Sy wonder of die kelner nog warm brood sal bedien.

You might see small variations depending on emphasis, especially around nog, but the final verb placement in the of-clause is the important part.

For example, a main-clause version would look different:

• Die kelner sal nog warm brood bedien.

So the key contrast is:

• main clause: sal appears earlier
• subordinate clause after of: sal bedien moves to the end

Here brood is being used in a general or mass-noun sense, like English bread.

So:

• warm brood = warm bread

No article is needed when talking about bread in a general sense.

Compare:

• Die kelner bedien brood. = The waiter serves bread.
• Die kelner bedien ’n brood. = The waiter serves a loaf of bread.

So without ’n, brood is understood as the substance or food item, not one specific loaf.

If you turned the embedded idea into a direct question, it would be:

• Sal die kelner nog warm brood bedien?
  = Will the waiter still serve warm bread?

Notice the difference:

• Direct question: Sal die kelner ... bedien?
• Embedded question: Sy wonder of die kelner ... sal bedien.

In the direct question, sal moves to the front. In the embedded question after of, the verbs go to the end.

Yes, very common.

It is a standard way to report uncertainty, curiosity, or indirect questions.

Common examples:

• Ek wonder of hy kom. = I wonder whether he is coming.
• Ons wonder of dit gaan reën. = We wonder whether it is going to rain.
• Sy vra of jy kan help. = She asks whether you can help.

So this sentence is useful because it shows a very common Afrikaans structure:

• main clause of thinking/asking
• followed by an of-clause with end-position verbs