Við berum timbrið og frauðplastið meðan hann skoðar raftækið.

Because bera is the infinitive meaning to carry / to bear, while berum is the present-tense form used with við (we).

So:

• að bera = to carry
• við berum = we carry / we are carrying

This is the normal verb agreement pattern in Icelandic: the verb changes to match the subject.

It can mean either, depending on context.

Icelandic often uses the simple present where English would use either:

• we carry
• we are carrying

So Við berum timbrið... meðan hann skoðar... can naturally describe an action happening right now, even though English often prefers the progressive form are carrying / is examining.

The ending -ið is the suffixed definite article, roughly equivalent to English the.

So:

• timbur = timber

• timbrið = the timber

• frauðplast = foam plastic / styrofoam

• frauðplastið = the foam plastic

• raftæki = electrical device / appliance
• raftækið = the electrical device / appliance

Unlike English, Icelandic usually attaches the to the end of the noun instead of using a separate word.

Because in Icelandic, if both nouns are definite, each noun normally gets its own definite ending.

So English:

• the timber and the foam plastic

matches Icelandic:

• timbrið og frauðplastið

You usually do not use one definite marker to cover both nouns. Each definite noun is marked individually.

They are direct objects, so they are in the accusative case.

Here:

• berum takes the objects timbrið og frauðplastið
• skoðar takes the object raftækið

Both bera and skoða commonly take the accusative.

A useful detail: these nouns are neuter singular, and for many neuter nouns the nominative and accusative look the same. So even though they are accusative here, the forms look unchanged apart from the definite ending.

Because they are being used as material / mass nouns.

Just like English can say:

• the timber
• the plastic
• the foam

Icelandic can use:

• timbrið
• frauðplastið

This does not necessarily mean there is only one piece. It refers to the material as a whole.

Meðan means while or during the time that. It introduces a subordinate clause.

So the structure is:

• Við berum timbrið og frauðplastið = main clause
• meðan hann skoðar raftækið = subordinate clause

It shows that the two actions happen at the same time.

Because meðan introduces a subordinate clause, and subordinate clauses in Icelandic do not follow the same verb-second pattern as main clauses.

So after meðan, the normal order is:

• hann skoðar raftækið

not a main-clause inversion pattern.

Compare:

• Við berum timbrið... = main clause
• meðan hann skoðar raftækið = subordinate clause

That difference in word order is very important in Icelandic.

No. Bera is a very common verb with several meanings, including:

• carry
• bear
• wear
• sometimes other extended meanings depending on context

In this sentence, because the objects are physical things like timber and foam plastic, the natural meaning is carry.

So context tells you which sense of bera is intended.

Yes, in this sentence they are all neuter nouns.

That helps explain the definite forms:

• timbrið
• frauðplastið
• raftækið

The ending -ið is a very common definite ending for neuter singular nouns.

Still, you should not rely only on spelling to guess gender. Icelandic noun gender is something you usually need to learn with the word itself.

You could say:

Meðan hann skoðar raftækið berum við timbrið og frauðplastið.

Notice what happens in the main clause:

• berum við instead of við berum

That is because Icelandic main clauses normally follow the verb-second rule. When the sentence starts with the meðan clause, the finite verb in the main clause comes before the subject.

So:

• Við berum... meðan hann skoðar...
• Meðan hann skoðar..., berum við...

Both are normal, but the word order changes.