Learn Hardcore Icelandic: Fyrirgefðu, hvar á að skrá sig?

Here á is not the preposition. It’s the 3rd person singular of the verb eiga used as a modal: eiga að + infinitive ≈ should/ought to/is supposed to. So á að skrá means “is supposed to register/should register.”

Why is there no subject (no “I/you/we”) in hvar á að skrá sig?

It’s an impersonal (subjectless) construction meaning “Where should one/people/you (in general) register?” Icelandic often omits an explicit subject for generic statements and keeps the verb in 3rd person singular.

Can I say Hvar á maður að skrá sig instead? Does it mean the same thing?

Yes. maður is the generic “one/you/people.” Both Hvar á að skrá sig? and Hvar á maður að skrá sig? are natural and essentially equivalent.

If I’m asking for myself, how do I say it?

Use a normal subject and the matching object of the reflexive:

I: Hvar á ég að skrá mig?
We: Hvar eigum við að skrá okkur?
You (plural): Hvar eigið þið að skrá ykkur?

Why is it sig and not mig/þig?

sig is the 3rd-person reflexive pronoun and refers back to a 3rd-person (here: generic/impersonal) subject. With a real 1st/2nd person subject, the pronoun must agree:

ég … skrá mig
þú … skrá þig
við … skrá okkur
þið … skrá ykkur
(maður/þeir/þær/þau) … skrá sig

Is skrá sig a set phrase? What happens if I drop sig?

Yes, skrá sig means “to register/sign up (oneself).” Without the reflexive, skrá means “to register/record” something or someone else. So dropping sig changes the meaning.

Why hvar and not hvert?

hvar asks for a location (where at).
hvert asks for direction (to where). Registering is treated as an activity located somewhere, so hvar fits. If you want the destination, you could say: Hvert á ég að fara til að skrá mig?

Why does the verb come right after hvar?

Icelandic has V2 word order in main clauses, including wh-questions: the finite verb sits in second position. Hvar takes the first slot; á (the finite verb) takes the second: Hvar á …? The initial Fyrirgefðu is just an interjection and doesn’t affect the clause’s V2 order.

What is the að here—“to” or “that”?

It’s the infinitive marker “to” introducing skrá. So á að skrá = “is supposed to register.” It’s not the conjunction “that.”

How formal is Fyrirgefðu? Could I use something else?

Fyrirgefðu: informal/singular “Excuse me/Sorry” to one person.
Fyrirgefið: polite/plural form.
Afsakið: neutral/polite “Excuse me,” safe with strangers or groups. All work fine before a question; choose based on formality and audience.

How do I ask about possibility instead of obligation (e.g., “Where can I sign up?”)?

Several natural options:

Hvar get ég skráð mig? (can I; using geta)
Hvar má ég skrá mig? (am I allowed to)
Hvar er hægt að skrá sig? (where is it possible to)

Why is there a comma after Fyrirgefðu?

Interjections like Fyrirgefðu, Afsakið, etc., are set off with a comma before the main clause. It mirrors English punctuation in “Excuse me, …”