Skifellene brukes under langrennsskiene.

Skifellene is the definite plural form of skifelle.

• skifelle = a ski skin / climbing skin
• skifellene = the ski skins

So the ending -ene is doing the job that English the does.

Because Norwegian usually puts definiteness on the end of the noun instead of using a separate word.

In this sentence:

• skifellene = the ski skins
• langrennsskiene = the cross-country skis

So English often has the + noun, but Norwegian often has noun + definite ending.

Brukes is the present passive form of bruke (to use).

So:

• bruke = to use
• brukes = is used / are used

In English, we say are used here because the subject is plural. In Norwegian, the form brukes stays the same.

Because brukes is passive, while bruker is active.

Compare:

• Vi bruker skifellene. = We use the ski skins.
• Skifellene brukes under langrennsskiene. = The ski skins are used under the cross-country skis.

The -s ending is a very common way to make passive sentences in Norwegian, especially in explanations, instructions, and factual descriptions.

No. Norwegian verbs do not change depending on whether the subject is singular or plural.

So:

• Skifellen brukes. = The ski skin is used.
• Skifellene brukes. = The ski skins are used.

The verb stays brukes in both cases.

It is a compound noun, which is very common in Norwegian.

It is made from:

• langrenn = cross-country skiing
• linking -s-
• ski = ski
• -ene = the (definite plural)

So langrennsskiene means the cross-country skis.

Because Norwegian likes to combine ideas into one word instead of several separate words.

English often writes:

• cross-country skis

Norwegian turns that into one compound:

• langrennsski

Then it adds the definite ending:

• langrennsskiene = the cross-country skis

This is very normal in Norwegian.

Because one s comes from the compound link, and the other is the first letter of ski.

So the word is built like this:

• langrenn
• -s-
• ski

That gives langrennsski, and then with the definite plural ending:

• langrennsskiene

Double consonants like this are common in Norwegian compounds.

Here under means underneath / on the underside of.

So the sentence is saying that the ski skins go on the bottom of the skis.

It does not mean during here. The meaning is physical location.

Because the sentence refers to the relevant, understood items: the ski skins and the skis they belong under.

In short explanatory or instructional Norwegian, this is very natural. It can sound a bit like:

• the ski skins
• the cross-country skis

even if the sentence is just giving general information.

Yes. Blir brukt is another passive form.

So these are both possible:

• Skifellene brukes under langrennsskiene.
• Skifellene blir brukt under langrennsskiene.

The version with brukes is shorter and often feels more neutral or instructional. The version with blir brukt can sound a little more explicit.