Aðalpersónan er fyndin.

It is made of:

• aðalpersóna = main character
• -n / -an = the suffixed definite article, meaning the

So aðalpersónan is the main character.

A useful thing to notice is that Icelandic often puts the at the end of the noun instead of using a separate word like English does.

That is the normal Icelandic pattern.

English says:

• the main character

Icelandic usually says:

• aðalpersónan

So the definite article is usually a suffix attached to the noun.

This is one of the first big differences English speakers notice in Icelandic.

Er is the present tense, 3rd person singular form of vera, which means to be.

So:

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

In Aðalpersónan er fyndin, er simply means is.

Because aðalpersóna is a feminine noun, and Icelandic adjectives must agree with the noun in:

• gender
• number
• case

The adjective fyndinn has these nominative singular forms:

• masculine: fyndinn
• feminine: fyndin
• neuter: fyndið

Since aðalpersónan is feminine singular, the correct form is fyndin.

Because fyndin is a predicative adjective: it comes after er and describes the subject.

In Icelandic, adjectives after vera are normally in the strong form:

• Aðalpersónan er fyndin. = The main character is funny.

But when the adjective comes directly before a definite noun, you normally use the weak form:

• fyndna aðalpersónan = the funny main character

So:

• er fyndin → predicative, strong form
• fyndna aðalpersónan → attributive with definite noun, weak form

This is a very common point of confusion for learners.

The subject aðalpersónan is in the nominative case.

The adjective fyndin is also effectively in the nominative, because with vera (to be), predicate adjectives normally match the subject in nominative.

So the sentence is built like this:

• Aðalpersónan — nominative feminine singular
• er — is
• fyndin — nominative feminine singular adjective

It would change to match the noun’s gender.

Examples:

• Maðurinn er fyndinn. = The man is funny.
• Barnið er fyndið. = The child is funny.
• Aðalpersónan er fyndin. = The main character is funny.

So the adjective changes like this:

• masculine: fyndinn
• feminine: fyndin
• neuter: fyndið

Not if you specifically mean the main character.

• aðalpersónan = the main character
• aðalpersóna = main character / a main character in a more general sense

In ordinary speech, a bare singular noun like aðalpersóna often sounds too general or incomplete if you mean a specific person in a story.

If you want an indefinite meaning, you would more naturally say:

• Ein aðalpersóna er fyndin. = A main character is funny.

So in your sentence, aðalpersónan is the natural choice if a specific character is meant.

A few useful pronunciation notes:

• ð in Aðal- is like the th in this
• á sounds roughly like ow in now
• ó is a long o sound
• y in fyndin is pronounced like Icelandic i

A rough English-friendly approximation might be:

• AÐ-al-per-SOH-nan er FIN-din

Also remember:

• Icelandic stress is usually on the first syllable of each word

So:

• AÐalpersónan
• ER
• FYNdin

The approximation is not perfect, but it is a helpful starting point.

You usually make a yes/no question by putting the verb first:

• Er aðalpersónan fyndin? = Is the main character funny?

That verb-first pattern is very common in Icelandic questions.

So:

• statement: Aðalpersónan er fyndin.
• question: Er aðalpersónan fyndin?

Add ekki after the verb:

• Aðalpersónan er ekki fyndin. = The main character is not funny.

So the basic pattern is:

• subject + er + ekki + adjective

Example:

• Hún er ekki fyndin. = She is not funny.

The normal, neutral order here is:

• Aðalpersónan er fyndin.

That is the most natural way to say it in everyday Icelandic.

You can change the order for special emphasis or style, but for a learner, the safest pattern is:

• subject + verb + adjective

So this sentence is a very good basic model to copy.