As jy hoes en koors het, moet jy vroeg gaan rus.

In Afrikaans, as often means if in conditional sentences.

So:

• As jy hoes en koors het, ... = If you have a cough and a fever, ...

Depending on context, as can also mean when, so sometimes learners have to rely on the situation to decide which is intended.

That is because As jy hoes en koors het is a subordinate clause introduced by as.

In Afrikaans, a subordinate clause often sends the finite verb to the end:

• main-clause style: Jy het koors.
• subordinate-clause style: as jy koors het

So het moves to the end of that clause because of the word as.

Because each clause needs its own subject.

The sentence has two parts:

• As jy hoes en koors het
• moet jy vroeg gaan rus

In both parts, the subject is jy = you.

English does the same thing:

• If you have a cough and a fever, you should go to bed early.

So repeating jy is completely normal.

Here, hoes is a verb: to cough / cough.

So:

• jy hoes = you cough / you are coughing

Afrikaans verbs usually do not change much according to the subject, so hoes stays the same.

Be careful, because English often says have a cough, while Afrikaans can simply say hoes for cough as a verb.

In Afrikaans, illness words and symptom words are often used without an article when speaking generally.

So:

• koors hê = to have a fever
• griep hê = to have flu

You do not need ’n here.

So koors het is the normal way to say have a fever.

Moet literally often means must / have to, but in health advice like this it can sound softer in English, closer to should.

So in this sentence, depending on tone and translation, it could be understood as:

• you must go to bed early
• you should go to bed early

Afrikaans moet often covers both ideas, and English chooses the most natural wording from context.

Gaan rus is a very common expression meaning go and rest or go to bed/rest.

Literally:

• gaan = go
• rus = rest

But together, it often functions like one natural action: go rest.

You could sometimes see just rus, but gaan rus sounds very idiomatic in this kind of sentence, especially when someone is being told to go lie down or go to bed.

Vroeg means early.

It is an adverb describing gaan rus:

• vroeg gaan rus = go to bed early / go rest early

Its position is normal in Afrikaans. Adverbs like vroeg often come before the infinitive verb group.

Because the sentence begins with the subordinate clause:

• As jy hoes en koors het, ...

After that opening clause, the main clause follows normal Afrikaans verb-second word order. That means the finite verb comes before the subject:

• As jy hoes en koors het, moet jy vroeg gaan rus.

Compare:

• Jy moet vroeg gaan rus.
• As jy hoes en koors het, moet jy vroeg gaan rus.

So once the as-clause comes first, moet moves in front of jy.

Yes, sometimes as can be translated as when, especially if the speaker assumes the situation is real or likely.

So depending on context, it could feel like:

• If you have a cough and a fever...
• When you have a cough and a fever...

In learner materials, if is often the clearest translation for this structure, but real usage can overlap.