Flaskekorken og sneipen finnes sammen.

Because -en is the usual definite singular ending for many masculine nouns in Norwegian. It works like English the attached to the end of the noun.

• en flaskekork = a bottle cap

• flaskekorken = the bottle cap

• en sneip = a cigarette butt
• sneipen = the cigarette butt

So instead of putting a separate word like the before the noun, Norwegian often adds the definite ending directly to the noun.

Yes. Norwegian normally writes compound nouns as one word.

Here:

• flaske = bottle
• kork = cork / cap
• flaskekork = bottle cap
• flaskekorken = the bottle cap

This is very common in Norwegian. Where English often uses two words, Norwegian often uses one compound word.

Sneip means cigarette butt or cigarette end. Sneipen is the definite form, so the cigarette butt.

It is a common everyday word. In this sentence it refers to a small piece left after a cigarette has been smoked.

Finnes comes from å finnes, which means to exist, to be found, or to occur.

In this sentence, finnes sammen means something like are found together or occur together.

So this is not about someone actively finding them at that moment. It is more about their being present together.

Because Norwegian verbs do not change for singular and plural the way English sometimes does.

In Norwegian, the present tense verb stays the same:

• den finnes = it is found / it exists
• de finnes = they are found / they exist

So finnes is correct whether the subject is one thing or several things.

Sammen means together.

In this sentence, it tells you that the bottle cap and the cigarette butt are together in some way, probably in the same place or found in association with each other.

So the structure is basically:

• Flaskekorken og sneipen = the bottle cap and the cigarette butt
• finnes = are found / exist
• sammen = together

Yes, they could be indefinite in a different context.

• En flaskekork og en sneip finnes sammen = A bottle cap and a cigarette butt are found together
• Flaskekorken og sneipen finnes sammen = The bottle cap and the cigarette butt are found together

The definite forms suggest that these are specific items already known from the context, or that the sentence is referring to them as identified objects.

It is understandable, but it sounds a little formal or observational.

Finnes sammen feels a bit like:

• are found together
• occur together

If you mean that the objects are physically lying next to each other, many speakers might say something more natural like:

• Flaskekorken og sneipen ligger sammen.
• Flaskekorken og sneipen ligger ved siden av hverandre.

So the original sentence is possible, but somewhat formal in tone.

The sentence follows normal Norwegian main-clause word order:

Flaskekorken og sneipen + finnes + sammen

That is:

• subject
• verb
• adverb

The whole phrase Flaskekorken og sneipen is the subject. Then comes the verb finnes, and then the adverb sammen.

Grammatically, yes, but it would usually sound less natural for objects like these.

Er sammen often means are together in a more general sense, and very often it is used about people, especially in the sense of being in a relationship.

For objects, Norwegian more naturally uses:

• ligger sammen if they are physically lying together
• finnes sammen if you mean they are found together
• hører sammen if you mean they belong together

So the best choice depends on the exact meaning you want.