Lestu umgengnisreglurnar og gestabókina frekar en að giska.

Lestu is the singular imperative of lesa (to read).

So the basic idea is:

• lesa = to read
• lestu! = read! (said to one person)

This -tu ending is a very common way of forming the imperative of many Icelandic verbs when speaking to one person.

If you were addressing more than one person, you would normally use:

• Lesið! = Read! (plural / formal)

So this sentence is telling one person to read something.

Because this is a command. In Icelandic, commands often start directly with the imperative verb.

So:

• Lestu ... = Read ...
• Komdu ... = Come ...
• Skrifaðu ... = Write ...

This is very natural in Icelandic, just as English commands usually begin with the verb:

• Read the rules
• Don’t guess

They are the direct objects of Lestu. Since lesa takes an object in the accusative case, both nouns appear in accusative forms.

Here is the breakdown:

• umgengnisreglurnar

  • dictionary form: umgengnisreglur
  • meaning: rules of conduct / house rules / visitor rules
  • form here: accusative plural definite
  • ending -nar becomes -urnar here because of the noun’s declension pattern

• gestabókina

  • dictionary form: gestabók
  • meaning: guestbook
  • form here: accusative singular definite

So the sentence is not just saying read rules and a guestbook, but read the rules and the guestbook.

Because they are different nouns with different number and declension patterns.

• umgengnisreglurnar

  • plural
  • definite
  • feminine noun pattern

• gestabókina

  • singular
  • definite
  • feminine noun pattern

Even though both nouns are feminine, Icelandic endings still change depending on whether the noun is singular or plural and which case it is in.

Very roughly:

• -ina often appears in feminine singular accusative definite
• -urnar often appears in feminine plural definite forms of certain noun types

So the different endings are completely normal and expected.

Yes. Umgengnisreglur is a compound noun.

It is built from:

• umgengni = conduct, behavior, way of dealing with something or being on a property
• reglur = rules

Together, umgengnisreglur means something like:

• rules of conduct
• house rules
• visitor guidelines
• rules for how to behave/use the place

This kind of compound is very common in Icelandic, and English speakers often need a little time to get used to how much meaning Icelandic packs into one word.

Frekar en að means rather than or instead of when comparing actions.

So the structure is:

• Lestu X frekar en að giska
• Read X rather than guess

It tells you that one action is preferable to another:

• do this
• instead of doing that

You can think of it as introducing the less desirable option.

Because giska is an infinitive here, and after frekar en Icelandic commonly uses að + infinitive.

So:

• að giska = to guess
• frekar en að giska = rather than guessing / rather than to guess

English often uses -ing after rather than, but Icelandic commonly uses að + infinitive in this structure.

So even though English says:

• rather than guessing

Icelandic says:

• frekar en að giska
• literally: rather than to guess

Yes. Giska can be used on its own to mean guess.

But it is also often used with á:

• giska á eitthvað = guess something / make a guess about something

For example:

• Ég giska á svarið. = I guess the answer.
• Ekki giska. = Don’t guess.

In your sentence, the point is general:

• read the rules and the guestbook rather than guessing

So no object is needed after giska.

Because Icelandic usually expresses the by attaching it to the end of the noun as a suffix, rather than using a separate word.

So:

• reglur = rules
• reglurnar = the rules

and:

• gestabók = guestbook
• gestabókin / gestabókina = the guestbook

This is one of the biggest structural differences from English. Instead of writing a separate word like the, Icelandic often builds definiteness directly into the noun.

Because og simply means and, and that is enough here.

The sentence is telling you to read two things:

• umgengnisreglurnar
• gestabókina

So:

• umgengnisreglurnar og gestabókina = the rules and the guestbook

There is no special extra grammar needed just because two direct objects are being listed.

Here are the main dictionary forms:

• Lestu → lesa = to read
• umgengnisreglurnar → umgengnisregla / more commonly plural umgengnisreglur = rules of conduct / house rules
• gestabókina → gestabók = guestbook
• frekar = rather, preferably
• en = than
• að = infinitive marker to
• giska = to guess

For learners, it is especially important to strip off the endings and identify the base forms:

• lestu → lesa
• reglurnar → reglur
• gestabókina → gestabók

Not necessarily. The imperative in Icelandic is often perfectly normal in instructions, notices, signs, and practical advice.

So Lestu ... can simply mean:

• Read ...
• Please read ...
• Make sure to read ...

Whether it sounds rude depends a lot on context and tone. In written instructions, it is usually just direct and practical.

For example, on a sign or in a guesthouse, this kind of wording would be very natural.

You would usually use the plural imperative:

• Lesið umgengnisreglurnar og gestabókina frekar en að giska.

So:

• Lestu = read! (to one person)
• Lesið = read! (to more than one person, or sometimes formal)

The rest of the sentence would stay the same.