Grillaftenen begynder nu.

Because Danish, like English, often forms compound nouns, but Danish does this even more consistently.

So grillaftenen breaks down like this:

• grill = grill / barbecue
• aften = evening
• grillaften = barbecue evening / grill evening
• grillaftenen = the barbecue evening

In Danish, compounds are normally written as a single word, so grill aften would be incorrect.

The -en is the definite article attached to the noun. In English, you usually put the before the noun, but in Danish, the definite article is often added to the end.

So:

• en grillaften = a barbecue evening
• grillaftenen = the barbecue evening

This is one of the most important differences between English and Danish nouns.

Because when a noun is definite and there is no adjective before it, Danish usually just adds the definite ending to the noun.

So:

• grillaftenen = the barbecue evening

You would use den when there is an adjective:

• den hyggelige grillaften = the cosy barbecue evening

So den grillaftenen is not the normal form here.

Begynder is the present tense of the verb at begynde, which means to begin or to start.

So:

• at begynde = to begin
• begynder = begin(s) / is beginning

In this sentence:

• Grillaftenen begynder nu. = The barbecue evening begins now. / The barbecue evening is starting now.

Danish present tense is the same for all subjects, so you do not change the verb depending on I, you, he, they, etc.

Because Danish is a verb-second (V2) language in main clauses. That means the finite verb usually comes in the second slot of the sentence.

Here the order is:

• Grillaftenen = first element
• begynder = second element
• nu = later element

So the sentence follows normal Danish word order.

You could also say:

• Nu begynder grillaftenen.

This is also correct, because nu is now the first element, and begynder still stays in second position.

Nu means now.

In this sentence, it gives the idea that the event is starting at this moment or right away:

• Grillaftenen begynder nu. = The barbecue evening starts now.

Depending on context, nu can sometimes also mean something like by now or at this point, but here the meaning is the straightforward now.

It can match either one, depending on context.

Danish present tense often covers both:

• begins
• is beginning
• is starting
• starts

So Grillaftenen begynder nu could naturally be translated as:

• The barbecue evening begins now
• The barbecue evening is starting now
• The barbecue evening starts now

English chooses among these a bit more carefully depending on style and situation; Danish often just uses the simple present form.

A rough learner-friendly breakdown is:

• grill
  • aften
    • en

Approximate pronunciation:

• gril-af-te-nən or gril-af-dənən, depending on speech style

A few useful notes:

• grill sounds fairly close to English grill
• aften is often pronounced more softly than it looks, and the t may be weak
• the final -en in definite nouns is often pronounced like a light -ən

The whole sentence is said smoothly, with the stress mainly on grillaftenen and nu.

Yes. Danish very commonly creates nouns by combining two nouns into one compound.

Some similar patterns are:

• sommeraften = summer evening
• filmaften = movie night
• familiefest = family party
• juleaften = Christmas Eve

So grillaften follows a very normal Danish pattern: one noun describes the type of another noun.

Yes, it sounds natural, especially in an announcement or event context.

For example, someone might say it:

• at a party
• in a program schedule
• over a loudspeaker
• when officially starting an event

In casual conversation, people might also say things like:

• Nu starter grillaftenen.
• Så begynder grillaftenen.

But Grillaftenen begynder nu. is perfectly correct and natural.