Lokahreingerningin tekur klukkustund.

Icelandic makes very heavy use of compound nouns, so what English often writes as two words is often written as one word in Icelandic.

Lokahreingerningin can be broken down like this:

• loka- = final, closing, end-
• hreingerning = cleaning
• -in = the attached definite article, meaning the

So Lokahreingerningin means the final cleaning or the finishing cleanup.

The -in is the definite article, so it corresponds to English the.

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

• lokahreingerning = final cleaning
• lokahreingerningin = the final cleaning

Here it is the nominative singular definite form of a feminine noun.

Tekur is the 3rd person singular present tense of the verb taka, meaning to take.

So:

• taka = to take
• tekur = takes

It is singular because the subject, Lokahreingerningin, is singular.

Yes. Icelandic uses taka in the same kind of time-expression that English does.

So:

• Lokahreingerningin tekur klukkustund. = The final cleaning takes an hour.

This is a very normal way to say that something requires a certain amount of time.

Other examples:

• Fundurinn tekur tvo tíma. = The meeting takes two hours.
• Það tekur langan tíma. = It takes a long time.

Because Icelandic does not have an indefinite article.

English distinguishes:

• an hour
• the hour

Icelandic only marks definiteness explicitly. So a bare noun like klukkustund can mean an hour in context.

That is why:

• tekur klukkustund = takes an hour

If you want to stress the number one, you can say:

• tekur eina klukkustund = takes one hour

That version is a bit more explicit or emphatic.

It is in the accusative, because it is the direct object of tekur.

In this kind of sentence, the amount of time is treated grammatically as the thing that is taken:

• tekur klukkustund = takes an hour

A useful thing to notice is that the form klukkustund looks the same in nominative and accusative singular, so the case is not visibly marked here.

You can see the accusative more clearly if you add one:

• eina klukkustund

The eina shows the accusative feminine singular form.

Yes, absolutely.

Both are possible:

• Lokahreingerningin tekur klukkustund.
• Lokahreingerningin tekur eina klukkustund.

The difference is roughly:

• tekur klukkustund = takes an hour
• tekur eina klukkustund = takes one hour

The second version puts a little more focus on the number.

This sentence uses the most basic Icelandic main-clause word order:

• subject + verb + object
• Lokahreingerningin + tekur + klukkustund

So it is very straightforward.

However, Icelandic also has a strong verb-second pattern in main clauses. That means if another element comes first, the finite verb usually still stays in second position.

For example:

• Venjulega tekur lokahreingerningin klukkustund. = Usually the final cleaning takes an hour.

So the sentence you were given is the neutral, standard order.

Klukkustund is the normal Icelandic word for hour as a unit of time.

It is historically a compound:

• klukka = clock
• stund = a period of time, a while, a moment

So it is literally something like clock-hour, but in modern Icelandic it simply means hour.

That makes the sentence very natural:

• tekur klukkustund = takes an hour