Sy bly by die huis, want sy het koors en pyn in haar kop.

In this sentence, bly means stay.

So Sy bly by die huis means She stays at home or She is staying at home.

Afrikaans bly can also mean live, depending on context:

• Ek bly in Kaapstad. = I live in Cape Town.
• Ek bly vandag by die huis. = I’m staying at home today.

So learners often need to decide from the situation which meaning fits best.

By die huis is the usual Afrikaans way to say at home.

• by = at / by
• die huis = the house / home

So although English says at home, Afrikaans often uses by die huis.

Compare:

• Sy is by die huis. = She is at home.
• Sy is in die huis. = She is in the house.

The second one focuses more on being physically inside the building. The first one is the normal everyday expression for at home.

Because the sentence has two clauses, and each clause needs its own subject.

• Sy bly by die huis
• want sy het koors en pyn in haar kop

The second sy means she again. Afrikaans does this just like English:

• She stays at home because she has a fever...

You normally do not leave out the second subject here.

Because want is a coordinating conjunction in Afrikaans, much like because in normal English word order.

So you get:

• Sy het koors... = normal main-clause order
• want sy het koors... = still normal order

That means the verb het stays after the subject sy.

Compare this with conjunctions like omdat, which do send the verb to the end:

• Sy bly by die huis, want sy het koors.
• Sy bly by die huis omdat sy koors het.

So:

• want → normal word order
• omdat → verb goes to the end

This is a very common learner question.

Het means has here.

• sy het koors = she has a fever
• sy het pyn = she has pain

Afrikaans uses het for have/has, just as English does in many expressions.

It is also used as an auxiliary in perfect tenses:

• Sy het gebly. = She stayed / has stayed.

But in your sentence, it is just the main verb to have.

Afrikaans often leaves out the indefinite article in certain illness expressions.

So:

• Sy het koors. = She has a fever.
• Ek het griep. = I have flu.
• Hy het kanker. = He has cancer.

This is very natural in Afrikaans. English often uses a in some of these cases, but Afrikaans does not always do that.

So het koors is normal, not incomplete.

Afrikaans often expresses this idea as pain in her head:

• pyn in haar kop

That is a very natural way to say someone has a headache or head pain.

You may also see:

• Sy het hoofpyn. = She has a headache.

So both ideas exist:

• hoofpyn = headache
• pyn in haar kop = pain in her head

The sentence you were given is using the more descriptive version.

Both kop and hoof can refer to the head, but kop is much more common in everyday speech.

• kop = normal everyday word for head
• hoof = more formal, less common in ordinary conversation, and often seen in compounds like hoofpyn

So:

• pyn in haar kop sounds very normal and conversational
• haar hoof is not what learners should usually use first in everyday speech

Because haar is the possessive form meaning her.

Compare:

• sy = she
• haar = her

So:

• Sy het pyn in haar kop. = She has pain in her head.

This is similar to English:

• she is the subject form
• her is the possessive/object form

Be careful, because Afrikaans sy can also mean his in other contexts:

• sy boek = his book

That can be confusing for English speakers.

It is grammatically simple present, but in meaning it can often be translated in different ways depending on context:

• She stays at home
• She is staying at home
• She remains at home

Afrikaans simple present often covers both the English simple present and present continuous.

So Sy bly by die huis can naturally mean She is staying at home in this context.

Usually, yes, in sentences like this.

• want = because / for

But in everyday learning, the safest translation is usually because.

Example:

• Ek gaan nie uit nie, want ek is moeg. = I’m not going out because I’m tired.

Just remember that want behaves differently from omdat in word order:

• want keeps normal order
• omdat sends the verb to the end

It would become:

Sy bly by die huis omdat sy koors en pyn in haar kop het.

Notice what changed:

• with want: want sy het koors...
• with omdat: omdat sy koors... het

So the verb het moves to the end of the clause after omdat.

Both sentences are correct, but the word order is different.

Yes, it is normally written with a comma here.

The sentence has two main clauses:

• Sy bly by die huis
• want sy het koors en pyn in haar kop

In standard written Afrikaans, a comma is typically used before want when it links two full clauses.

So the punctuation in the sentence is normal and correct.