Ons praat hieroor.

Ons is the Afrikaans subject pronoun for we.

A useful thing to know is that ons can also mean us in other sentences, depending on its role:

• Ons praat hieroor. = We are talking about this.
• Hy sien ons. = He sees us.

So ons covers both we and us, and the sentence structure tells you which meaning it has.

In Afrikaans, verbs usually do not change according to the subject the way they do in English.

So you get:

• Ek praat = I talk / I am talking
• Jy praat = you talk / you are talking
• Ons praat = we talk / we are talking
• Hulle praat = they talk / they are talking

That makes Afrikaans verbs much simpler than English in this respect.
In this sentence, praat stays praat no matter that the subject is ons.

Hieroor means about this.

It is made from:

• hier = this / here
• oor = about / over

So:

• hieroor = about this
• daaroor = about that

This is a very common Afrikaans pattern. Instead of using a separate phrase like English about this, Afrikaans often uses one combined word.

Because in Afrikaans, words like hieroor, daaroor, waaroor, daarvan, hierin, and similar forms are normally written as single words.

These are often called pronominal adverbs in grammar terms: a demonstrative or question element combines with a preposition.

For example:

• hieroor = about this
• daaroor = about that
• waaroor = about what / why
• daarvan = of that / from that

So hieroor is not written as hier oor in this meaning.

You may hear or understand oor dit, but in normal Afrikaans, hieroor or daaroor is usually the more natural choice when English would say about this or about that.

So these are more idiomatic:

• Ons praat hieroor. = We are talking about this.
• Ons praat daaroor. = We are talking about that.

Using oor dit is generally less natural in this kind of sentence.

It can mean either, depending on context.

Afrikaans often uses the simple present where English might use either:

• we talk
• we are talking

So Ons praat hieroor can mean:

• We talk about this.
• We are talking about this.

In real usage, context usually makes the meaning clear.

This is the normal Afrikaans main-clause order:

subject + verb + rest

So:

• Ons = subject
• praat = verb
• hieroor = the rest of the predicate

Afrikaans is a verb-second language in main clauses, which means the finite verb comes early in the sentence. In a simple statement like this, that gives you the straightforward order:

• Ons praat hieroor.

You can move hieroor to the front for emphasis:

• Hieroor praat ons.

That is possible, but less neutral.

The difference is basically the same as this versus that in English.

• hieroor = about this
• daaroor = about that

So if the thing being discussed is close, present, immediate, or just introduced, hieroor is natural.
If it is more distant, already mentioned, or treated as that matter, daaroor is often used.

Examples:

• Ons praat hieroor. = We are talking about this.
• Ons praat later daaroor. = We’ll talk about that later.

You would usually say:

Ons praat nie hieroor nie.

Afrikaans commonly uses a double nie pattern in ordinary negation:

• nie after the verb or later in the clause
• another nie at the end of the clause

So:

• Ons praat hieroor. = We are talking about this.
• Ons praat nie hieroor nie. = We are not talking about this.

This double negative structure is one of the most important features of Afrikaans grammar.

A rough English-friendly guide would be:

ons praat heer-oor

A few details:

• ons sounds roughly like ons in English, but with a short vowel
• praat has a long aa sound, something like praht
• hieroor is roughly heer-oor

The r sound may vary depending on accent, and Afrikaans pronunciation can differ by region, but that approximation will help a beginner say it understandably.

Yes — this sentence shows two very useful Afrikaans patterns:

1. Verbs usually do not change form

   • ek praat
   • ons praat
   • hulle praat

2. Afrikaans often uses combined forms like hieroor

   • hieroor = about this
   • daaroor = about that
   • waaroor = about what / why

If you remember those two ideas, this sentence becomes much easier to understand and reuse.