Is hierdie tafel ons s'n, of is dit hulle s'n?

Because this is a yes/no question. In Afrikaans, yes/no questions usually put the finite verb first.

• Statement: Hierdie tafel is ons s'n. = This table is ours.
• Question: Is hierdie tafel ons s'n? = Is this table ours?

So the word order is similar to English in questions like Is this table ours?

Hierdie means this.

So:

• hierdie tafel = this table

It is used for something near the speaker, just like English this. A common contrast is:

• hierdie = this
• daardie = that

Here, of means or.

So the middle of the sentence:

• ..., of is dit hulle s'n?
  means
• ..., or is it theirs?

This can confuse learners because of may look unfamiliar, and in some languages related to Afrikaans it can have other uses too. In this sentence, though, it simply means or.

Dit means it.

In of is dit hulle s'n?, the dit refers back to hierdie tafel. English does the same thing:

• Is this table ours, or is it theirs?

Afrikaans repeats the idea with dit instead of repeating hierdie tafel again.

Because ons s'n is a possessive form meaning ours.

Afrikaans often uses possessive word + s'n when the noun is understood and does not need to be repeated.

So:

• ons s'n = ours
• hulle s'n = theirs

In this sentence, the noun tafel has already been mentioned, so Afrikaans uses the possessive form:

• Is hierdie tafel ons s'n? = Is this table ours?

The s'n part helps show that you mean the one belonging to us.

S'n is a shortened possessive form used in expressions like:

• ons s'n = ours
• hulle s'n = theirs
• Jan s'n = Jan's one / Jan's

It is very common in Afrikaans when you want to say that something belongs to someone without repeating the noun.

For example:

• Dit is my boek. = It is my book.
• Die boek is myne / my s'n. = The book is mine.

In your sentence, ons s'n and hulle s'n work the same way.

They are used differently.

• ons tafel = our table
  
  • used before a noun
• ons s'n = ours
  
  • used when the noun is already known or already mentioned

So:

• Ons tafel is groot. = Our table is big.
• Hierdie tafel is ons s'n. = This table is ours.

English makes the same distinction:

• our table
• ours

Yes. Ons can mean:

• we
• us
• our / ours in possessive expressions

You figure out the meaning from the grammar around it.

In this sentence:

• ons s'n

it clearly means ours, because it is part of a possessive expression.

Examples:

• Ons eet nou. = We are eating now.
• Hy sien ons. = He sees us.
• Dis ons s'n. = It is ours.

Because hierdie already determines the noun.

In Afrikaans, you normally do not say die hierdie tafel. You just say:

• hierdie tafel = this table

This is similar to English, where you say this table, not the this table.

Yes. Tafel means table, and it is related to English table and Dutch tafel. Many Afrikaans words are recognizable to English speakers, although spelling and pronunciation may differ.

So:

• tafel = table

A rough English-friendly guide is:

• hierdie ≈ HEER-dee
• s'n ≈ sun with a very weak vowel, or suhn

So:

• ons s'n sounds roughly like ons sun
• hulle s'n sounds roughly like HUL-luh sun

That said, exact pronunciation depends on accent, and the vowel in s'n is usually short and unstressed.

In normal full speech and writing, repeating is dit is natural and clear:

• Is hierdie tafel ons s'n, of is dit hulle s'n?

This matches English:

• Is this table ours, or is it theirs?

You may hear shorter, more conversational ellipsis in speech, but for learners the full version is the best model. It clearly shows the structure of both alternatives.