Die simptoom is ernstig.

Yes. In this sentence, die is the definite article, so it means the.

A useful thing to know is that Afrikaans uses die for:

• singular nouns: die simptoom = the symptom
• plural nouns: die simptome = the symptoms

Unlike English, Afrikaans does not change the definite article for number or gender.

Yes. Simptoom is a clear cognate of English symptom. They have the same basic meaning, but the Afrikaans spelling follows Afrikaans spelling patterns.

So:

• English: symptom
• Afrikaans: simptoom

The double oo in Afrikaans usually shows a long vowel sound.

Because ernstig comes after the verb is, so it is being used predicatively.

In Afrikaans:

• after a linking verb like is, adjectives usually stay in their basic form
  
  • Die simptoom is ernstig.
• before a noun, adjectives often take -e
  
  • die ernstige simptoom = the serious symptom

So:

• predicative: Die simptoom is ernstig.
• attributive: die ernstige simptoom

This is one of the most important adjective patterns in Afrikaans.

Yes, in this simple sentence it is very similar to English:

• Die simptoom = subject
• is = verb
• ernstig = adjective/complement

So the structure is:

Subject + verb + adjective

That is why the sentence feels quite familiar to an English speaker.

Basically yes. Is is the present-tense form of the verb wees (to be) used with a singular subject here.

So:

• Die simptoom is ernstig. = The symptom is serious.

This is one of those convenient cases where Afrikaans and English look very similar.

A rough pronunciation guide is:

die → like dee
simptoom → roughly simp-tohm
is → like iss
ernstig → roughly AIRN-stikh or EARN-stikh

A few notes:

• die in Afrikaans is not pronounced like the English verb die
• g in ernstig is the typical Afrikaans guttural g/ch sound, made at the back of the throat
• the oo in simptoom is a long vowel

Afrikaans does not use grammatical gender the way languages like German or Dutch do.

That means you do not need to learn different forms of the for masculine, feminine, or neuter nouns. You just use die as the definite article.

So:

• die tafel = the table
• die man = the man
• die vrou = the woman
• die simptoom = the symptom

This makes Afrikaans articles much simpler than in many other European languages.

You would say:

Die simptome is ernstig.

Changes:

• simptoom → simptome for the plural
• die stays the same
• ernstig stays the same
• is is often used in Afrikaans where English would use are

That last point is important: Afrikaans commonly uses is with plural predicate structures in standard usage.

Yes, but the meaning changes.

• Die simptoom is ernstig. = The symptom is serious.
• ’n simptoom is ernstig. = A symptom is serious.

So die makes it definite, while ’n makes it indefinite.

Also note:

• ’n is unstressed and usually pronounced like a very weak uh
• in writing, it is always written with the apostrophe: ’n

Yes. Ernstig can mean:

• serious
• severe
• grave

The exact English translation depends on context.

For example:

• Die situasie is ernstig. = The situation is serious.
• Die besering is ernstig. = The injury is severe.

So in a medical sentence like this, serious or severe may both fit depending on the wider context.