Jeg vil være med i fagforeningen.

In this sentence, vil means "want to", not "will".

• Jeg vil være med i fagforeningen = I want to be in / I want to join the union.
• If you translated vil as "will" here, it would sound wrong in English: "I will be in the union" suggests a prediction or promise, not a wish.

In Norwegian, vil can mean both:

• want (to) – expressing desire:
  
  • Jeg vil spise. = I want to eat.
• will (future-like), but that usage is less direct and depends on context.

No. Norwegian does not have a separate future tense the way English does, and vil is not a general future marker here.

In Jeg vil være med i fagforeningen, vil expresses desire/intent, not just future time.

• Future in Norwegian is often expressed simply with the present tense and context:
  
  • I morgen er jeg med i fagforeningen. = Tomorrow I am in the union.
• Jeg vil være med ... = I want to be / I wish to be / I intend to be ...

Both are common, but they’re used differently:

• være med = to be part of, to be included in, to take part (as an ongoing state)

  • Jeg vil være med i fagforeningen.
    → I want to be (a member) in the union.

• bli med = to come along / to join (a specific event or action)

  • Vil du bli med på møtet?
    → Do you want to come along to the meeting?

If you said:

• Jeg vil bli med i fagforeningen, it would usually be understood as "I want to join the union" (the act of joining),
  while
• Jeg vil være med i fagforeningen focuses more on being part of it (as a member), though in practice people might use it to mean “join” too.

You really need med here.

• være med i is a fixed, very common pattern when talking about being part of a group, team, club, or activity:
  
  • være med i kor = be in a choir
  • være med i et lag = be on a team
  • være med i fagforeningen = be in the union

Jeg vil være i fagforeningen is grammatically possible, but it sounds unusual and could be interpreted more literally as "I want to be inside the union" (physically), not "be a member of it."
To talk about membership, prefer være med i (or være medlem av, see next question).

Yes, you can, and it’s perfectly correct:

• Jeg vil være medlem av fagforeningen.
  = I want to be a member of the union.

Differences in feel:

• være med i fagforeningen

  • More colloquial and natural in everyday speech.
  • Emphasizes being part of the group.

• være medlem av fagforeningen

  • Slightly more formal or explicit.
  • Emphasizes your status as a member.

Both are normal and idiomatic; in casual spoken Norwegian, være med i is extremely common.

fagforeningen is a compound word with a definite ending:

• fag = trade / profession / subject
• forening = association / society / union
• en fagforening = a trade union

Then it’s put in the definite singular:

• fagforeningen = the trade union

So the whole sentence:

• Jeg vil være med i fagforeningen.
  Literally: I want to be along/part in the trade-union-the.
  Natural English: I want to be in / join the union.

Using the definite form fagforeningen implies a specific union that both speaker and listener know about:

• Jeg vil være med i fagforeningen.
  → The union at this workplace / in this context.

If you say:

• Jeg vil være med i en fagforening.
  → I want to be in a union (in general, not necessarily a specific one you’ve already identified).

So:

• definite (fagforeningen) = a particular, known union.
• indefinite (en fagforening) = any union, not specified which.

fagforening is a feminine (or common-gender) noun in Bokmål. You can treat it either as feminine or as “common gender” (the en/et system), but most people use it as feminine in speech.

Common forms (Bokmål):

• Indefinite singular: en fagforening (or ei fagforening in more feminine-style Bokmål)
• Definite singular: fagforeningen (or fagforeninga in some dialects / Nynorsk-like forms)
• Indefinite plural: fagforeninger
• Definite plural: fagforeningene

In the sentence you gave, fagforeningen is definite singular.

For membership in an organization, i is the standard preposition:

• være med i fagforeningen = be in the union
• være med i et band = be in a band
• være med i en klubb = be in a club

på is not used with fagforening for membership.
You might use på with some activities or events:

• være med på møtet = be in / take part in the meeting
• være med på laget (also possible in some varieties) = be on the team

But for an organization as a member, i is the safe, standard choice: i fagforeningen.

You can say it, but it sounds different:

• Jeg vil være med i fagforeningen.
  → I want to be in the union. (focus on desire)

• Jeg skal være med i fagforeningen.
  → More like I am going to / I’m supposed to / I will be in the union.
  It can suggest a plan, arrangement, or even obligation, rather than your personal wish.

In other words:

• vil = desire/intention: you want this.
• skal = planned/fated/decided: this will happen, or is arranged, or you’re expected to.

For expressing your wish to join, vil is more natural.

Vil is neutral and very common; it’s not rude or pushy by itself.

If you want a softer or more polite way to say the same idea (depending on context), you can use:

• Jeg har lyst til å være med i fagforeningen.
  = I would like to be in the union / I feel like being in the union.

This sounds a bit milder or more tentative than Jeg vil være med ..., which is more straightforward and decisive: I want to be in the union.

In standard Eastern Norwegian, a rough guide for an English speaker:

• Jeg – often pronounced like “yai” (some dialects have something closer to “jæi” or even “je”).
• vil – like English “vill” (short i, as in “fill”).
• være – approximately “VAE-reh” (the æ like a in “cat”; final -e is a short, relaxed eh/uh).
• med – like “meh” (short e, final d often very soft or almost silent).
• i – like English “ee” in “see”.
• fagforeningen – roughly: “FAHG-foh-RAIN-ingen”
  
  • fag: fahg (long a, like in British “father”; g pronounced)
  • for: like English “for” but shorter
  • en: short “en”
  • ingen: “ing-en” (with ng as in “sing”, and a short final en)

Spoken quickly, syllables blend:
Jeg vil være med i fagforeningen → something like:
yai vil VAE-reh meh ee FAHG-foh-RAIN-ingen.