Die oorlog stop die handel.

Because both oorlog (war) and handel (trade / commerce) are definite nouns here.

So the structure is:

• Die oorlog = the war
• die handel = the trade / trade

Afrikaans often uses die the way English uses the.

Yes, here die means the.

But it is not pronounced like English die.
It is pronounced roughly like dee.

So:

• die = the
• pronunciation: roughly dee

Because Afrikaans verbs do not usually change form for different subjects in the present tense.

So you get:

• ek stop = I stop
• jy stop = you stop
• hy/sy stop = he/she stops
• die oorlog stop = the war stops

Unlike English, Afrikaans does not add -s for he/she/it.

Yes, in this simple sentence it is.

The pattern is:

• Die oorlog = subject
• stop = verb
• die handel = object

So it follows the basic subject–verb–object order, just like English:

• The war stops trade

No. Afrikaans does not have grammatical gender in the same way that languages like German or Dutch do.

That means:

• oorlog is not masculine or feminine in everyday grammar
• handel is not masculine or feminine either
• the article stays die

So you do not have to learn different forms of the for different noun genders.

No. Afrikaans is simpler here than English learners may expect.

Die is the normal definite article for:

• singular nouns
• plural nouns
• all genders

So die can mean:

• the war
• the wars
• the trade

The sentence is perfectly normal with die in both places.

Here it is a noun, because it comes after the article die:

• die handel = the trade / commerce

In other contexts, handel can also be related to verbal ideas such as to act or to deal, but in this sentence it is clearly a noun.

Not necessarily.

The simple present in Afrikaans can be used for:

• a general fact
• a current situation
• a habitual action

So Die oorlog stop die handel can mean something like:

• The war stops trade
• The war is stopping trade

The exact sense depends on context.

It can often be translated naturally as just trade in English.

Even though Afrikaans uses die, English may sound better without the in some contexts. So depending on style and context, die handel could be translated as:

• the trade
• trade
• commerce

So the Afrikaans article does not always have to be matched word-for-word in English.

A rough English-friendly guide is:

• oorlog ≈ OOR-loch
  
  • the g is a guttural Afrikaans sound, not a normal English g
• handel ≈ HAN-dəl

And the whole sentence is roughly:

• dee OOR-loch stop dee HAN-dəl

These are only approximations, but they are useful for getting started.