Bóluplastið og pakkalímbandið eru á borðinu.

The ending -ið is the definite article attached to the end of a noun. Icelandic usually puts the on the noun itself instead of using a separate word.

So:

• bóluplast = bubble wrap
• bóluplastið = the bubble wrap

and

• pakkalímband = packing tape / parcel tape
• pakkalímbandið = the packing tape

In this sentence, both nouns are neuter singular, and -ið is the normal definite ending for nominative/accusative singular neuter.

Because the subject is two things joined by og (and):

• Bóluplastið
• og pakkalímbandið

Together, they make a plural subject, so the verb must also be plural:

• er = is
• eru = are

So:

• Bóluplastið er á borðinu = The bubble wrap is on the table.
• Bóluplastið og pakkalímbandið eru á borðinu = The bubble wrap and the packing tape are on the table.

This is a very common Icelandic case pattern.

With á, Icelandic uses:

• dative for location: on something
• accusative for movement toward something: onto something

Here, the sentence describes where the items already are, so it uses location, which means dative:

• á borðinu = on the table

If you were talking about putting them onto the table, you would use the accusative:

• Settu það á borðið = Put it onto the table.

So the contrast is:

• eru á borðinu = are on the table
• fara á borðið = go onto the table

They are in the nominative case because they are the subject of the sentence.

You can think of the structure like this:

• Bóluplastið og pakkalímbandið = subject
• eru = verb
• á borðinu = prepositional phrase showing location

Since they are the things doing the being, they appear in the nominative.

Borðinu is dative singular definite of borð (table).

Breakdown:

• borð = table
• borðinu = the table, in the dative singular

It is dative because á takes the dative when it means on in a static location sense.

So:

• á borðinu = on the table

Because they are in different cases.

All three nouns are neuter singular, but:

• Bóluplastið and pakkalímbandið are nominative definite
• borðinu is dative definite

For many neuter nouns:

• nominative definite singular: -ið
• dative definite singular: -inu

So:

• borðið = the table
• borðinu = the table (in dative)

That difference is about grammar, not meaning in the basic dictionary sense.

In this sentence, both are singular.

Even though bubble wrap and packing tape can refer to material rather than countable objects, Icelandic treats each word here as a singular noun:

• bóluplastið = the bubble wrap
• pakkalímbandið = the packing tape

The whole subject becomes plural only because there are two singular nouns joined by og.

Yes, all three nouns here are neuter:

• bóluplast — neuter
• pakkalímband — neuter
• borð — neuter

Yes, it matters, because gender affects things like:

• the form of the definite article
• adjective endings
• sometimes pronouns and other agreement patterns

For example, the neuter definite singular often shows up as:

• -ið in nominative/accusative
• -inu in dative

That is why you see:

• bóluplastið
• pakkalímbandið
• borðinu

Yes — Icelandic uses a lot of compound nouns.

Both bóluplast and pakkalímband are compounds:

• bóluplast = roughly bubble + plastic
• pakkalímband = roughly package + glue + strip/band

This is very normal in Icelandic. Instead of using several separate words, Icelandic often builds one long noun.

A useful habit is to look for smaller parts inside the word. That often makes vocabulary much easier to remember.

Yes, Icelandic word order is somewhat flexible, though the sentence you have is the most straightforward neutral order.

Normal order here:

• Bóluplastið og pakkalímbandið eru á borðinu.

You could also front the location for emphasis:

• Á borðinu eru bóluplastið og pakkalímbandið.

That means essentially the same thing, but it gives more focus to on the table.

A key rule in Icelandic is that the finite verb often stays in the second position in main clauses. So when a different element comes first, the verb usually comes right after it.

You would remove the definite endings.

So:

• Bóluplast og pakkalímband eru á borði.

However, that can sound less natural in many situations, depending on context. More commonly, you might still want a definite noun in the location phrase, or the sentence might be phrased differently depending on what exactly you mean.

The main thing to notice is:

• bóluplastið = the bubble wrap
• bóluplast = bubble wrap

and

• pakkalímbandið = the packing tape
• pakkalímband = packing tape

Icelandic does not use a separate word for the in these ordinary noun phrases.

A rough English-friendly guide would be:

BOH-lu-plast-ith ohg PAK-ka-leem-band-ith EH-ru ow BOR-thi-nu

A few notes:

• ó is a long vowel, roughly like o in go
• í is like ee
• ð is like the th in this
• r is usually trilled or tapped
• the stress in Icelandic normally falls on the first syllable of the word

So the main stresses are on:

• BÓluplastið
• PAKkalímbandið
• BORðinu

That would be:

Bóluplastið er á borðinu.

You just remove the second noun, so now the subject is singular:

• Bóluplastið = singular subject
• therefore er = is

Likewise:

Pakkalímbandið er á borðinu.
= The packing tape is on the table.

This is a good way to see the difference between:

• er = is
• eru = are

when you compare one noun vs. two nouns joined by og.