Hann skellti bókinni á borðið.

Skellti is the 3rd person singular past tense of the verb skella.

So in this sentence it means that he did the action, and that the action happened in the past. The dictionary form is skella.

A useful thing to notice is the ending -ti, which is a common past-tense marker in some Icelandic weak verbs.

Because the verb skella takes its object in the dative in this kind of sentence.

English speakers often expect the direct object to be like an accusative object, but Icelandic does not always work that way. Some verbs simply require a different case, and skella is one of them here.

So:

• bókinni = dative singular definite
• not bókina = accusative singular definite

This is something you often have to learn with the verb.

No. It is still the main object of the verb, even though it is in the dative.

That is important for English speakers, because in English we often connect dative-like meaning with indirect object, but Icelandic case does not map that neatly onto English grammar.

A good way to think about it is:

• case tells you what form the noun takes
• it does not automatically tell you whether something is direct or indirect in the English-school-grammar sense

People often call this a quirky case or quirky object.

Because á can take two different cases, depending on meaning:

• accusative for movement toward / onto
• dative for location on

Here the book is being moved onto the table, so Icelandic uses á + accusative:

• á borðið = onto the table

If you were just saying that something is on the table, with no movement, you would use the dative:

• á borðinu = on the table

Because with neuter singular nouns, the nominative and accusative are often identical.

So borðið can be either nominative or accusative in form. You know it is accusative here because of the grammar of the phrase:

• á
  • movement = accusative

So the case is shown by the construction, not by a special visible ending in this particular word.

They are part of the case + definite article system.

Icelandic usually puts the definite article onto the end of the noun instead of using a separate word like English the.

So here:

• bókinni = book-the in the dative singular
• borðið = table-the in the nominative/accusative singular

That means both nouns are definite: the book, the table.

Not always exactly. Skella usually gives a sense of something being done abruptly, forcefully, or with a bang / sharp impact.

Depending on context, English might translate it as things like:

• slam
• bang
• throw down
• plonk
• shut hard

So the core idea is not just movement, but movement with force or suddenness.

This sentence has a very normal, neutral order:

• Hann = subject
• skellti = finite verb
• bókinni = object
• á borðið = prepositional phrase

But Icelandic word order is somewhat flexible because of its case system. Still, in a main clause Icelandic usually follows the V2 rule, which means the finite verb tends to stay in second position.

So you can move other parts for emphasis, but the verb usually stays second:

• Á borðið skellti hann bókinni.
• Bókinni skellti hann á borðið.

These versions are more marked and change the emphasis.

In ordinary finite sentences, yes, you normally keep the subject pronoun.

Unlike languages such as Spanish or Italian, Icelandic usually does not drop subject pronouns just because the verb ending already tells you the person.

So Hann skellti bókinni á borðið is the normal full sentence. Without hann, it would usually sound incomplete unless the context made the subject exceptionally clear.