Grillstarteren står ved grillkullene.

Because Danish usually puts the definite article onto the end of the noun.

• en grillstarter = a grill starter
• grillstarteren = the grill starter

So the -en here is doing the job that English the does.

A useful general pattern is:

• common-gender noun: -en
• neuter noun: -et

Danish often uses position verbs for location, where English would often just use is.

Here, står literally means stands, and it is used because the grill starter is thought of as being in an upright position.

So Danish prefers:

• Grillstarteren står ved grillkullene.

rather than a more neutral:

• Grillstarteren er ved grillkullene.

The version with er is not impossible, but står sounds more natural and more specific.

Ved usually means by, next to, near, or sometimes at.

In this sentence, it shows that the grill starter is located close to the charcoal, not inside it or on top of it.

Compare:

• ved = by / next to / near
• i = in / inside
• på = on

So ved grillkullene means something like by the charcoal or next to the coals.

Because grillkullene is a definite plural form.

It means the coals or the charcoal, depending on how you translate it naturally in English.

Danish often makes the definite plural with -ene.
So this ending is functioning like the ...s in English.

This word can be slightly tricky because English often uses charcoal as a mass noun, while Danish may use a plural-looking form where English would not.

Because in Danish, the definite article is usually attached to the noun itself.

That is why you get:

• grillstarteren = the grill starter
• grillkullene = the coals / the charcoal

English uses a separate word (the), but Danish usually uses endings instead.

One important extra point: if there is an adjective before the noun, Danish often uses a separate definite word as well:

• den varme grillstarter = the hot grill starter

Yes. Danish makes a lot of compound nouns, just like English does.

• grillstarter = grill
  • starter
• grillkul = grill
  • kul

The last part is the main part of the word, and that part usually determines the grammar of the whole compound.

This is very common in Danish, so getting comfortable with compounds is important.

Yes. This is a very normal main-clause word order:

• Grillstarteren = subject
• står = verb
• ved grillkullene = place expression

So it follows the basic pattern:

subject + verb + adverbial

That said, Danish is a verb-second language, so if you move another element to the front, the verb still stays in second position:

• Ved grillkullene står grillstarteren.

That structure is also correct.

Usually not here, unless the grill starter is physically lying on its side.

Danish distinguishes between different kinds of location:

• står = standing upright
• ligger = lying down
• sidder = sitting / attached / positioned in a certain way

A grill starter would normally be upright, so står is the natural choice.

If it had fallen over, then ligger might make sense instead.

The definite form suggests that the speaker means specific charcoal/coals that are known from the situation.

So grillkullene means something like:

• the charcoal
• the coals

If you said just grillkul, that would sound more general, like charcoal as a substance rather than a specific set of coals in the situation.

Danish often uses definite forms when the thing is identifiable from context, even when English might sometimes sound less definite.