Þetta er snilld.

Þetta means this or this thing.

In this sentence, it is a demonstrative pronoun, pointing to something nearby in the conversation or situation. English often just says this, but Icelandic uses a form that also shows grammatical gender and number.

Here, þetta is the neuter singular form.

Icelandic has related forms that depend on how the word is being used.

• þetta = this as a standalone pronoun, often meaning this thing / this situation / this
• þessi is often used more like this before a noun, depending on the noun phrase

So:

• Þetta er snilld. = This is brilliant / This is genius.
• Þessi bók = this book

A learner will often notice that Icelandic demonstratives change form more than English ones do.

Er means is.

It is the present tense of the verb að vera, which means to be.

So:

• ég er = I am
• þú ert = you are
• það/þetta er = it/this is

In Þetta er snilld, er simply links þetta and snilld, just like English is.

Snilld is a noun, not an adjective.

Its basic meaning is something like:

• genius
• brilliance
• sheer brilliance

So although English might naturally say This is brilliant, Icelandic uses a noun:

• Þetta er snilld.
• literally: This is genius / This is brilliance
• naturally: This is brilliant.

This kind of noun-for-evaluation expression is very common in Icelandic.

Because Icelandic often does not use an indefinite article like English a/an.

English says:

• This is genius
• This is a masterpiece
• This is brilliance

Icelandic has no separate word for a/an. A noun can appear without an article and still make perfect sense.

So snilld on its own is normal here.

After vera (to be), Icelandic often uses the nominative case for the predicate noun.

So in:

• Þetta er snilld

both parts are in the expected basic form.

For a beginner, the important point is:

• er does not force an object case here
• snilld is describing what þetta is

This works similarly to English This is genius, where genius is not an object but a complement.

Yes. Snilld is very common, especially in speech, when reacting positively to something.

It can mean that something is:

• brilliant
• excellent
• a great idea
• cleverly done

So Þetta er snilld is a very natural way to say things like:

• This is brilliant.
• This is genius.
• This is शानदार? No, in English: This is amazing.
• What a great idea.

It is often enthusiastic and approving.

A rough English-friendly guide is:

• Þetta ≈ THET-ta
  
  • þ sounds like th in think, not like th in this
• er ≈ ehr
• snilld ≈ roughly snilt

So the whole sentence is approximately:

THET-ta ehr snilt

A few notes:

• Icelandic pronunciation is not always obvious from spelling.
• In snilld, the written ll does not sound like a normal English ll.
• It is better to treat the whole word as sounding roughly like snilt until you learn the finer details.

The normal word order here is:

• Þetta = subject
• er = verb
• snilld = complement

So:

• Þetta er snilld.

This is the most neutral and natural order for a simple statement like This is brilliant.

Icelandic word order can sometimes move around for emphasis, but for a basic sentence like this, the standard order is exactly what you see.

Yes. That is one reason þetta is so useful.

It can refer to almost anything the speaker is reacting to, such as:

• an idea
• a solution
• a movie scene
• a joke
• a piece of design
• a plan
• food
• an event

So the sentence is very flexible. It does not have to refer only to a physical object. It can refer to a whole situation: This is brilliant.

It is generally neutral to informal and very natural in everyday language.

It is not rude or slangy, but it is also not especially formal. You could use it in conversation very easily.

In a more formal or written style, someone might choose a different expression depending on context, but Þetta er snilld is perfectly normal Icelandic and very common in speech.