Getið þér sagt mér hvort sendingin sé komin?

Because this is a direct question. In Icelandic main-clause yes/no questions, the finite verb usually comes first, followed by the subject.

So:

• Getið þér ...? = question word order
• Þér getið ... would not be the normal way to ask it

Notice that this only applies to the main clause. Inside the embedded clause after hvort, the word order is different.

Getið is the present tense, 2nd person plural form of geta, meaning can / be able to.

The relevant forms are:

• ég get
• þú getur
• hann/hún/það getur
• við getum
• þið getið
• þeir/þær/þau geta

Here it is used with þér, which takes plural verb agreement.

Þér is a formal/polite way of addressing one person. It is grammatically treated like 2nd person plural, which is why the verb is getið rather than getur.

So:

• Getur þú ...? = informal, normal everyday singular
• Getið þér ...? = formal/polite singular

In modern Icelandic, þú is much more common in everyday speech. Þér can sound formal, old-fashioned, or very respectful depending on context.

Because segja takes the person you tell in the dative case.

So:

• segja mér = tell me
• segja þér = tell you
• segja honum = tell him

That is why you get mér, not ég or mig.

A useful pattern is:

• segja einhverjum eitthvað = tell someone something

Here the person being told is mér.

Hvort introduces an indirect yes/no question, and it usually corresponds to whether in English.

So the structure is roughly:

• Getið þér sagt mér hvort ... = Can you tell me whether ...

This is different from a direct yes/no question. Compare:

• Er sendingin komin? = Has the shipment arrived?
• ... hvort sendingin sé komin = ... whether the shipment has arrived

Sé is the present subjunctive form of vera.

• er = indicative present
• sé = subjunctive present

In Icelandic, the subjunctive often appears in subordinate clauses involving reported, uncertain, requested, or non-factual information. After expressions like Can you tell me whether ..., the subjunctive is quite natural, especially in more careful or formal language.

So:

• hvort sendingin sé komin = a more formal/literary-type phrasing
• hvort sendingin er komin = also possible, especially in more everyday speech

Sendingin is the noun sending with the definite article attached at the end.

• sending = shipment, delivery, dispatch
• sendingin = the shipment / the delivery

Icelandic usually adds the as a suffix rather than as a separate word. That is why you see -in attached to the noun.

Also, sending is a feminine noun, which matters for agreement later in the sentence.

Because komin agrees with sendingin, which is feminine singular.

The participle behaves like an adjective here, so it matches the noun in gender and number:

• kominn = masculine singular
• komin = feminine singular
• komið = neuter singular

Since sendingin is feminine singular, the correct form is komin.

More or less, yes. Icelandic often uses vera + kominn/komin/komið to express the idea that someone or something has arrived and is now there.

So sendingin er komin means something like:

• the shipment has arrived
• the shipment is here now

This construction emphasizes the resulting state, not just the event of coming.

Yes, but the nuance is a little different.

• sendingin er komin focuses on the fact that the shipment has arrived and is now here
• sendingin hefur komið focuses more on the event has come / has arrived

In many everyday situations, er komin is the more natural way to talk about arrivals.

Because after hvort, you are inside a subordinate clause, and Icelandic usually uses more statement-like word order there.

So the pattern is:

• hvort + subject + verb + complement

That gives:

• hvort sendingin sé komin

You do not normally use the same inversion as in a main yes/no question.

Compare:

• Main question: Er sendingin komin?
• Embedded question: hvort sendingin sé komin

A more everyday version would often be:

• Getur þú sagt mér hvort sendingin er komin?

That version is less formal because it uses:

• þú instead of þér
• getur instead of getið

You may also hear sé replaced by er in ordinary speech. So the original sentence is correct, but it sounds more formal and polished than casual everyday conversation.