De frisdrank en de versiering zijn klaar.

De means the here.

It is used because both frisdrank and versiering are de-words (common-gender nouns), so each noun takes de in the singular:

• de frisdrank
• de versiering

Dutch normally repeats the article with each noun in a phrase like this, so de frisdrank en de versiering is the natural form.

Because the subject is plural.

Even though frisdrank and versiering are each singular by themselves, they are joined by en (and), so together they form a plural subject:

• De frisdrank is klaar.
• De versiering is klaar.
• De frisdrank en de versiering zijn klaar.

So Dutch uses zijn, the plural form of to be.

Because klaar is used after the verb zijn, as a predicative adjective.

In Dutch, adjectives used after verbs like zijn, worden, or blijven usually do not take the -e ending:

• De frisdrank is klaar.
• De versiering is klaar.
• De frisdrank en de versiering zijn klaar.

This is different from adjectives placed before a noun, where an -e ending is often added:

• de mooie versiering

So here klaar stays unchanged.

Grammatically, frisdrank is singular.

The plural form is frisdranken, but in everyday Dutch, frisdrank is often used as a mass noun, a bit like soft drink or soda in English. Depending on context, de frisdrank can refer to:

• the soft drink
• the soda
• the soft drinks as a category or supply

So even though the noun is singular in form, it may refer to the drinks collectively.

Yes. Versiering is grammatically singular, but it can refer to decoration in a collective sense.

So in context, de versiering may mean:

• the decoration
• the decorating
• the decorations as a set

If you want to emphasize separate individual decorations, Dutch can also use the plural versieringen.

The structure is:

• De frisdrank en de versiering = subject
• zijn = finite verb
• klaar = predicate adjective

So the sentence follows a very straightforward Dutch main-clause pattern:

subject + verb + complement

That is why it looks quite close to English in structure.

In Dutch, you usually make a yes/no question by putting the finite verb first:

• Zijn de frisdrank en de versiering klaar?

So the statement:

• De frisdrank en de versiering zijn klaar.

becomes the question:

• Zijn de frisdrank en de versiering klaar?

It can mean either, depending on context.

With zijn, klaar often means:

• ready
• finished
• all set

In this sentence, it most naturally means that the soft drinks and the decorations are ready or prepared. The exact nuance depends on the situation, but all set is often a good natural English feeling for klaar.

Learners should normally keep both articles:

• De frisdrank en de versiering zijn klaar.

That is the clearest and most standard form. Since both nouns are separate definite nouns, repeating de is the normal choice.

Leaving out the second de may sound compressed or less natural in many contexts, so it is better to include it.