Hún lýsir ljósmyndinni.

Because hún is the subject form, meaning she.

In Icelandic, pronouns change form depending on their role in the sentence, just like English she/her. Since she is the one doing the action, Icelandic uses hún, not an object form.

Lýsir is the present tense, 3rd person singular form of the verb lýsa.

So:

• að lýsa = the infinitive, to describe
• ég lýsi = I describe
• þú lýsir = you describe
• hún lýsir = she describes

Here it matches hún, so lýsir means describes.

That ending shows two things at once:

• the noun is definite: the photograph
• the noun is in the dative singular

So ljósmyndinni means the photograph, but specifically in the grammatical form required here.

This is very common in Icelandic: the ending carries information that English usually expresses with separate words or word order.

Because the verb lýsa takes a dative object, not an accusative one.

That is something English speakers often have to get used to: in Icelandic, many verbs require a specific case for their object.

So even though English simply says describe the photograph, Icelandic uses:

• lýsa
  • dative

That is why you get ljósmyndinni, not ljósmyndina.

In Icelandic, the is usually attached to the end of the noun instead of standing as a separate word.

So:

• ljósmynd = photograph
• ljósmyndin = the photograph
• ljósmyndinni = to/for/in/on the photograph, or after a verb that requires dative, simply the photograph in the dative form

So the idea of the is built into ljósmyndinni.

Ljósmynd is a feminine noun, and yes, that matters.

In Icelandic, a noun’s gender affects:

• its article ending
• its case endings
• any words that agree with it

The form -inni here is the feminine definite dative singular ending.

This is the normal, straightforward word order:

• Hún = subject
• lýsir = verb
• ljósmyndinni = object

So it follows the basic pattern Subject – Verb – Object.

However, Icelandic is also a verb-second language in main clauses. That means the finite verb usually stays in the second position. So other word orders are possible for emphasis, as long as the verb stays second.

Yes. Icelandic pronouns reflect grammatical gender, so hún can also refer to a feminine noun as it.

For example, if you were talking about a feminine-gender noun, Icelandic might use hún where English would use it.

In this sentence, though, if the meaning given is she describes the photograph, then hún refers to a female person.

Yes. It is made from:

• ljós = light
• mynd = image, picture

So ljósmynd literally has the sense of light-image, which is a nice way to remember that it means photograph.

No. Lýsa can have several related meanings depending on context, such as:

• describe
• portray
• illuminate / light up

So the exact meaning comes from the sentence around it. Here, since the meaning has already been given to the learner, describe is the intended sense.