Die antwoord is eenvoudig.

Here die is the definite article, so it means the.

A few useful things to know about die in Afrikaans:

• It does not change for gender.
• It can be used with both singular and plural nouns.
• In this sentence, die antwoord means the answer.

Also, die in Afrikaans is usually pronounced dee, not like the English word die.

Because die and 'n do different jobs:

• die antwoord = the answer (a specific answer)
• 'n antwoord = an answer / a answer (any answer, not specific)

So if you are talking about a particular answer already known from the context, die is the natural choice.

Is is the Afrikaans present-tense form of to be.

One very helpful thing for English speakers is that Afrikaans does not conjugate this verb in the present tense the way English does. You get:

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

So in this sentence, is simply links die antwoord and eenvoudig.

Because here the adjective comes after is and describes the subject. In that position, Afrikaans normally uses the basic adjective form:

• Die antwoord is eenvoudig.

But when the adjective comes before the noun, it often takes -e:

• die eenvoudige antwoord = the simple answer

So this is the contrast:

• Die antwoord is eenvoudig.
• die eenvoudige antwoord

In this sentence, yes. The pattern is:

• subject
  • is
    • adjective

So:

• Die antwoord = subject
• is = linking verb
• eenvoudig = adjective

That looks very similar to English: The answer is simple.

However, Afrikaans word order changes in some other structures. For example:

• Môre is die antwoord eenvoudig. = Tomorrow the answer is simple.
• Ek weet dat die antwoord eenvoudig is. = I know that the answer is simple.

So this sentence is straightforward, but Afrikaans does have word-order rules that go beyond English.

It can be both.

In Die antwoord is eenvoudig, antwoord is a noun because it follows the article die.

But Afrikaans also uses antwoord as a verb:

• Ek antwoord die vraag. = I answer the question.
• Hy antwoord vinnig. = He answers quickly.

So the same word can function as either a noun or a verb, just as answer can in English.

It would be:

• Die antwoorde is eenvoudig. = The answers are simple.

Notice what changes and what does not:

• antwoord → antwoorde becomes plural
• die stays die
• is stays is
• eenvoudig stays eenvoudig

That is one of the nice simplifications in Afrikaans: fewer form changes than in English.

Usually yes, or very close to it. Eenvoudig often means simple, plain, or uncomplicated.

But English speakers should be careful not to confuse simple with easy in every context. Afrikaans often uses maklik for easy:

• Die antwoord is eenvoudig. = The answer is simple.
• Die toets is maklik. = The test is easy.

Sometimes the ideas overlap, but they are not always interchangeable. Eenvoudig focuses more on something being not complicated.