Fluesoppen er en soppart.

The dictionary form is en fluesopp.

The ending -en is the usual definite singular ending for many common-gender nouns in Bokmål. So:

• en fluesopp = a fly agaric / a toadstool
• fluesoppen = the fly agaric / the toadstool

So Fluesoppen is just the definite form of fluesopp.

This is a very common pattern in Norwegian.

• Fluesoppen is the subject, and here it refers to the species/kind as a whole.
• en soppart is a classification after er, so it is normally indefinite.

The structure is:

• X er en Y = X is a Y

So Fluesoppen er en soppart means that the thing called fluesoppen belongs to the category soppart.

This is similar to generic sentences in English such as The tiger is a mammal.

Because soppart is a singular countable noun, and in Norwegian, singular countable nouns usually need an article.

So:

• en soppart = a mushroom/fungus species

After er, when you are saying what something is, Norwegian normally keeps that article:

• Det er en bil.
• Hunden er et dyr.
• Fluesoppen er en soppart.

Leaving out en here would sound wrong in standard Norwegian.

Because Norwegian normally writes compound nouns as one word.

Here:

• sopp = mushroom / fungus
• art = species

Together:

• soppart = mushroom species / fungus species

This is very typical in Norwegian. English often uses two words where Norwegian uses one:

• book store → bokhandel
• school bus → skolebuss
• mushroom species → soppart

Both nouns are commonly treated with en in Bokmål:

• en fluesopp
• en soppart

That gives forms like:

• fluesoppen = definite singular
• sopparten = definite singular

For this sentence, the important thing to remember is:

• en for the indefinite singular
• -en for the definite singular

Er is the present tense of å være, which means to be.

So:

• å være = to be
• er = is / am / are

Norwegian does not change the present-tense verb the way English does. So the same form er is used with different subjects:

• jeg er
• du er
• han er
• de er

Normally, no.

A bare singular count noun like fluesopp usually cannot stand alone like that in standard Norwegian. You would normally need either:

• an article: En fluesopp er en soppart
• or the definite form: Fluesoppen er en soppart

So Fluesopp er en soppart sounds incomplete or unnatural in ordinary Norwegian.

Normally, no.

When Norwegian uses a noun after er to classify something, it usually keeps the article:

• Han er en lærer
• Det er en feil
• Fluesoppen er en soppart

So Fluesoppen er soppart would not be the normal form here.

The basic order is:

• subject + verb + complement

So here:

• Fluesoppen = subject
• er = verb
• en soppart = complement

This is the normal order in a simple Norwegian main clause.

A useful extra rule is that in Norwegian main clauses, the finite verb usually comes in second position. So if another element comes first, the verb still stays second:

• I skogen er fluesoppen lett å kjenne igjen.

Because Norwegian does not capitalize common nouns.

So unlike German, words like fluesoppen and soppart are written in lowercase unless they begin the sentence.

In this sentence, Fluesoppen has a capital F only because it is the first word of the sentence.

A simple English-style approximation would be:

• Fluesoppen ≈ FLOO-eh-sop-pen
• er ≈ air or a short ehr, depending on accent
• en soppart ≈ en SOPP-art

A couple of useful pronunciation notes:

• Double consonants, as in pp, usually mean the vowel before them is short.
• Norwegian pronunciation varies by dialect, so exact sounds can differ.

If you want, a rough overall approximation is:

FLOO-eh-sop-pen ehr en SOPP-art