Ég set eina skóflu af mold í beðið.

set is the 1st person singular present tense of setja: ég set = I put / I am putting.

A few useful comparisons:

• ég set = I put / I am putting
• ég setti = I put / I was putting / I placed

Icelandic often uses the simple present where English might use either I put or I am putting, depending on context.

Because einn (one) has to agree with the noun it describes in gender, number, and case.

Here it describes skóflu, and skófla is:

• feminine
• singular
• accusative

So the correct form is eina.

Compare:

• ein skófla = one shovel (nominative)
• eina skóflu = one shovel / one shovelful (accusative)

Because skóflu is the accusative singular form of skófla.

In this sentence, eina skóflu af mold is the direct object of set, so it goes into the accusative case.

Basic forms:

• skófla = nominative singular
• skóflu = accusative singular

So:

• Ein skófla er hér. = One shovel is here.
• Ég set eina skóflu af mold... = I put one shovel/shovelful of soil...

In this sentence, it most naturally means a shovelful of soil.

Literally, skófla means shovel or spade, but Icelandic can use words like this to refer to the amount carried by the tool. So eina skóflu af mold is a natural way to say one shovelful of soil.

Here af links the quantity expression to the material:

• eina skóflu af mold = one shovelful of soil

This is similar to English expressions like:

• a cup of tea
• a bag of flour
• a shovel of soil

So af here is functioning like of in English.

After af, Icelandic normally uses the dative.

So mold here is dative. The important thing is that the form just happens to look the same as the dictionary form.

For mold, the singular forms are often not visibly different in the places a learner expects, so even though the case is dative after af, you still see mold.

So the rule is:

• af
  • dative

even if the noun’s form does not visibly change.

Because mold is being used as a mass noun or material noun, like soil, sand, or water in English.

So here it means soil in a general sense, not the specific soil.

• af mold = of soil
• af moldinni would mean something more like of the soil

In sentences about materials or substances, Icelandic often leaves the article off unless the substance is specific and already known.

The -ið is the definite article attached to the noun.

• beð = bed
• beðið = the bed

This is very common in Icelandic: instead of putting a separate word for the before the noun, Icelandic usually adds it to the end.

So here:

• í beðið = into the bed

Most likely beð here means a garden bed or flower bed, not a sleeping bed.

Because í can take either accusative or dative, depending on meaning:

• accusative = motion into
• dative = location in

Here there is movement: the soil is being put into the bed. So Icelandic uses the accusative:

• í beðið = into the bed

If you were describing something already located there, you would use the dative instead:

• í beðinu = in the bed

This accusative/dative contrast after prepositions is very important in Icelandic.

This is normal Icelandic main-clause word order:

• Ég = subject
• set = finite verb
• eina skóflu af mold = object
• í beðið = prepositional phrase

So the structure is basically:

Subject + Verb + Object + Place/Direction

Also, Icelandic is a verb-second (V2) language, which means the finite verb usually comes very early in the clause, typically in the second position in main clauses.

Yes, in other contexts beðið can also be a verb form, which can confuse learners.

But in this sentence, it is clearly the noun beð with the definite article:

• í beðið = into the bed

The preposition í strongly signals that this is a noun phrase here, not a verb. Context makes the meaning clear.