Hvernig sem setningin byrjar, þarf hún að enda á punkti.

In this sentence, hvernig sem means however or no matter how.

It introduces the idea that the beginning can vary, but the result in the main clause still applies:

Hvernig sem setningin byrjar, þarf hún að enda á punkti.
= However a sentence begins, it has to end with a period/full stop.

So this is not a literal word-for-word how as translation. It is a fixed Icelandic pattern.

In Icelandic, words like hvað, hver, hvar, hvenær, and hvernig can combine with sem to give a meaning like no matter what, whoever, wherever, whenever, or however.

So:

• hvernig = how
• hvernig sem = however / no matter how

Here, sem helps create that indefinite, open-ended meaning. It is part of the construction, not something you should try to translate too literally on its own.

Because setningin is the definite form: the sentence.

In Icelandic, the definite article is usually attached to the end of the noun:

• setning = sentence / a sentence
• setningin = the sentence

So setningin is made up of:

• setning = sentence
• -in = the definite ending here

Because setning is a feminine noun in Icelandic.

Icelandic pronouns follow grammatical gender, not natural gender. So even though sentence is an inanimate thing, it is referred to as:

• hún if the noun is feminine
• hann if the noun is masculine
• það if the noun is neuter

So in this sentence, hún means it, referring back to setningin.

This is because of Icelandic verb-second word order in main clauses.

The sentence starts with a fronted subordinate clause:

Hvernig sem setningin byrjar, ...

After that, the main clause begins, and in Icelandic the finite verb typically comes first in the main clause after such an opening element:

• þarf hún að enda ...

So the order is:

1. fronted clause
2. finite verb
3. subject

Compare:

• Hún þarf að enda á punkti. = It has to end with a period.
• Hvernig sem setningin byrjar, þarf hún að enda á punkti.

That inversion is very normal in Icelandic.

Þarf is the 3rd person singular present tense of að þurfa = to need / have to / must.

Here it agrees with hún:

• hún þarf = it needs to / it has to

So the main clause literally says something like:

it needs to end with a period

In natural English, that is often translated as it must end with a period or it has to end with a period.

Because að enda is the infinitive, and it comes after þarf.

After þurfa, Icelandic normally uses að + infinitive:

• þarf að fara = needs to go
• þarf að lesa = needs to read
• þarf að enda = needs to end

So:

• endar = ends or is ending as a finite verb
• að enda = to end

In this sentence, þarf is the finite verb, so the next verb stays in the infinitive.

Punkti is dative singular.

The basic noun is:

• punktur = point / dot / period
• punkti = dative singular form

It appears after the preposition á in the expression enda á punkti.

Many Icelandic prepositions require a specific case, and here á takes the dative in this expression. So learners usually need to remember the whole phrase:

að enda á punkti = to end with a period / full stop

Yes, literally it is something like on a period/point, but idiomatically it means with a period or in a period as the ending punctuation mark.

This is a good example of Icelandic using a preposition where English would not necessarily use the same one. So it is best to learn it as a set phrase:

enda á punkti = end with a period

Here punktur means the punctuation mark period in American English or full stop in British English.

The word punktur can also mean point or dot in other contexts, but in this sentence the punctuation meaning is clearly intended.

So:

• punktur = point / dot / period
• here: period / full stop

Because the first part is a subordinate clause:

Hvernig sem setningin byrjar, ...

The comma separates that introductory clause from the main clause:

... þarf hún að enda á punkti.

That is standard and natural punctuation in Icelandic. It helps show the structure clearly:

• subordinate clause first
• main clause second

Yes. Byrjar is the 3rd person singular present tense of að byrja = to begin / to start.

It agrees with setningin:

• setningin byrjar = the sentence begins

So the first clause literally means:

however the sentence begins

Yes. The core main clause is:

Setningin þarf að enda á punkti.
= The sentence has to end with a period.

The opening clause Hvernig sem setningin byrjar adds the meaning however it begins / no matter how it begins.

So the full sentence emphasizes that the rule about ending with a period stays true regardless of how the sentence starts.