Klifurgrindin er ný, og litla stelpan klifrar upp á hana aftur eftir hádegi.

Icelandic very often builds nouns as compounds.

• klifur = climbing
• grind = frame, rack, climbing structure

So klifurgrind is a compound noun meaning a climbing frame or jungle gym.

The ending -in is the definite article attached to the noun, so:

• klifurgrind = a climbing frame
• klifurgrindin = the climbing frame

Unlike English, Icelandic usually puts the at the end of the noun rather than as a separate word.

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

Here, klifurgrindin is:

• feminine
• singular
• nominative

So the adjective must also be feminine singular nominative:

• masculine: nýr
• feminine: ný
• neuter: nýtt

That is why the sentence says Klifurgrindin er ný.

This is a very common Icelandic pattern.

• lítil stelpa = a little girl
• litla stelpan = the little girl

When an adjective comes before a definite noun, the adjective usually takes the weak form.

Here:

• the noun is definite: stelpan = the girl
• so the adjective is weak: litla

The adjective lítill is irregular, so its forms change quite a bit:

• lítil stelpa = a little girl
• litla stelpan = the little girl

So litla stelpan is exactly what you expect for the little girl.

klifrar is the present tense, 3rd person singular, of the verb að klifra = to climb.

Because the subject is singular, litla stelpan, the verb is singular too:

• ég klifra = I climb
• þú klifrar = you climb
• hún klifrar = she climbs

So stelpan klifrar means the girl climbs / is climbing.

Because hana is an object form, while hún is a subject form.

Compare:

• hún = she / it, nominative
• hana = her / it, accusative

In this sentence, the pronoun is not the subject of the clause. It comes after the preposition phrase upp á, so you need the object form hana.

Also, it refers back to klifurgrindin, which is feminine, so the feminine pronoun is used.

This is about a very important Icelandic contrast:

• accusative after á for motion onto
• dative after á for location on

Here the girl is moving onto the climbing frame, so Icelandic uses the accusative:

• upp á hana = up onto it

If you were describing being located on it, you would normally expect dative instead:

• uppi á henni = up on it

So:

• movement toward/on to something → hana
• location on something → henni

upp á makes the upward movement more explicit.

With climbing, Icelandic very naturally says:

• klifra upp á = climb up onto

That fits the action very well, because climbing usually involves moving upward onto something.

You may sometimes see just á, but upp á is especially natural when the idea is up onto rather than simply onto.

aftur usually means either:

• again
• back

In this sentence, it most naturally means again: the girl climbs onto it another time.

Its position is fairly flexible in Icelandic. You could also hear things like:

• klifrar aftur upp á hana
• klifrar upp á hana aftur

Both are possible, though the exact emphasis can shift slightly.

eftir hádegi is a time expression meaning after noon or in the afternoon.

• eftir = after
• hádegi = noon

So the phrase places the action later in the day.

A useful grammar point: eftir often takes the dative, and here the form hádegi is the correct form in this expression.

Because Icelandic uses grammatical gender, not just natural gender.

The noun klifurgrind is feminine, so when you refer back to it, you use feminine pronouns:

• nominative: hún
• accusative: hana
• dative: henni

Even though a climbing frame is not female in any natural sense, its grammatical gender is feminine. English mostly avoids this by using it, but Icelandic does not.

The word order can change more than in English, but Icelandic still follows an important rule: in a main clause, the finite verb usually comes in second position.

The clause here is:

• og litla stelpan klifrar upp á hana aftur eftir hádegi

This is a normal neutral order with the subject first.

But you could front another element, especially for emphasis, and the verb would still stay in second position:

• og eftir hádegi klifrar litla stelpan upp á hana aftur

So Icelandic is flexible, but not random. The verb placement is one of the key things learners need to watch.