Die vergadering is Donderdag.

Here die means the.

In Afrikaans, die is the normal definite article for singular and plural nouns. Unlike English, it does not change for gender, and unlike Dutch, Afrikaans does not switch between different definite articles. So:

• die vergadering = the meeting

Usually no, not in normal standard Afrikaans.

If you mean the meeting as a specific event, you normally need the article:

• Die vergadering is Donderdag.

Leaving out die would sound incomplete in ordinary usage.

Vergadering is a noun meaning meeting.

It is the subject noun in this sentence, together with die:

• Die vergadering = the subject
• is = the verb
• Donderdag = the time expression

Afrikaans often leaves out the preposition in simple sentences like this when stating the day of an event.

So:

• Die vergadering is Donderdag.

naturally means:

• The meeting is on Thursday.

This is very common and idiomatic.

Yes, you can.

Op Donderdag is also correct, and it is a more explicit way to say on Thursday. But in a short, simple sentence, Afrikaans very often just says:

• Die vergadering is Donderdag.

So both are possible, but the version without op is very natural.

Because names of days are normally used without an article when you are simply naming the day.

So:

• Donderdag = Thursday

You would not normally say die Donderdag in this sentence.

Yes. This sentence follows a very similar pattern to English:

• Die vergadering = subject
• is = verb
• Donderdag = complement/time expression

So the structure is close to:

• The meeting is Thursday
• or more naturally in English, The meeting is on Thursday

Yes. Afrikaans uses is with all persons in the present tense:

• ek is = I am
• jy is = you are
• hy is = he is
• ons is = we are
• hulle is = they are

So in that way, Afrikaans is simpler than English.

Yes. That is grammatical.

Putting Donderdag first gives it more emphasis, as if you are highlighting the day:

• Donderdag is die vergadering.

The more neutral version is still:

• Die vergadering is Donderdag.

In a yes-no question, Afrikaans usually puts the verb first:

• Is die vergadering Donderdag?

That means:

• Is the meeting on Thursday?

Afrikaans normally uses a double nie:

• Die vergadering is nie Donderdag nie.

This means:

• The meeting is not on Thursday.

A common Afrikaans pattern is:

• subject + verb + nie + rest + nie

You may also hear:

• Die vergadering is nie op Donderdag nie.

That is also correct.

A rough English-friendly guide is:

• dee fer-KHAA-duh-ring is DON-der-dakh

A few helpful notes:

• die sounds like dee, not like English die
• g in Afrikaans is usually a throaty sound, like the ch in some Scottish pronunciations of loch
• Donderdag has strong stress on the first syllable: DON-der-dakh