Spennan er mikil.

Spennan is the definite form of the noun spenna.

• spenna = tension / excitement / suspense
• spennan = the tension / the excitement / the suspense

In Icelandic, the definite article is usually attached to the end of the noun instead of being a separate word like English the.

So:

• spenna = indefinite
• spennan = definite

Er is the present-tense form of the verb vera (to be).

So here it simply means is.

A few common forms of vera are:

• ég er = I am
• þú ert = you are
• hann/hún/það er = he/she/it is

In Spennan er mikil, er links the subject spennan with the description mikil.

Because the adjective has to agree with the noun in gender, number, and usually case.

The noun spenna is:

• feminine
• singular
• here, nominative

So the adjective must also be feminine singular nominative, which is mikil.

Compare:

• mikill = masculine singular
• mikil = feminine singular
• mikið = neuter singular

Since spennan is feminine, mikil is the correct form.

That is a very common question. In Icelandic, when an adjective is used predicatively—that is, after a verb like vera (to be)—it normally appears in the strong form, not the weak form.

So:

• Spennan er mikil. = correct
• not Spennan er mikla.

Even though spennan is definite, the adjective is not directly standing before the noun. It comes after er, so it is a predicate adjective.

Compare:

• mikla spennan = the great tension
  Here the adjective comes before the noun, so weak declension is used.
• spennan er mikil = the tension is great
  Here the adjective comes after er, so strong declension is used.

Spenna is a feminine noun.

One clue is that many Icelandic nouns ending in -a are feminine, although this is not a perfect rule. In practice, gender has to be learned with each noun.

It is useful to memorize nouns together with:

• their gender
• their article form
• sometimes a full phrase

For example:

• spenna (f.)
• spennan
• mikil spenna

That makes it easier to remember which adjective forms go with it.

Yes. This sentence follows a very familiar pattern:

• Spennan = subject
• er = verb
• mikil = subject complement / predicate adjective

So it is structurally like:

• The tension is high
• The excitement is great

This is one of the more straightforward Icelandic sentence patterns.

Not always. Spenna can mean different but related things depending on context, such as:

• tension
• suspense
• excitement

So Spennan er mikil could fit different situations:

• in a thriller: The suspense is great
• before a game: The excitement is high
• during conflict: The tension is high

The exact English choice depends on the situation.

Yes, but it changes the feel of the sentence.

• Spennan er mikil = The tension/excitement is high
  This usually refers to a specific tension or excitement in the situation.
• Spenna er mikil = Tension/excitement is high or There is much tension/excitement
  This sounds more general or less tied to one clearly defined situation.

In many real contexts, the definite form spennan is the more natural choice.

A simple learner-friendly approximation is:

SPEN-nan er MIH-kil

A few helpful points:

• Stress is usually on the first syllable in Icelandic words.
• spennan starts with spen-, like spen in spend, but without the d.
• mikil has the stress on mi-.
• The r in er is pronounced, unlike many English accents.

You do not need a perfect native accent right away; the most important thing is getting the stress in roughly the right place.

You would change er to var:

• Spennan var mikil. = The tension/excitement was high.

Everything else stays the same because the subject and adjective agreement do not change here.

So:

• er = is
• var = was

Yes. This is a very common Icelandic pattern:

[definite noun] + er + [adjective agreeing with the noun]

For example:

• Veðrið er gott. = The weather is good.
• Bókin er góð. = The book is good.
• Stúlkan er glöð. = The girl is happy.

So Spennan er mikil is a useful model sentence for building many others.