Íslenskan er falleg, en tungumálið er erfitt.

Because Icelandic often puts the definite article on the end of the noun instead of using a separate word like the.

• íslenska = Icelandic / the Icelandic language in some contexts
• íslenskan = the Icelandic language more explicitly

In this sentence, Íslenskan means Icelandic as a specific language, so the ending -an is the definite article attached to the noun.

This is very common in Icelandic:

• bók = book
• bókin = the book

So íslenskan is basically íslenska + the.

For the same reason: it is the noun tungumál (language) with the definite article added.

• tungumál = language
• tungumálið = the language

The ending looks different from -an because Icelandic noun endings depend on gender, number, and case.

Here:

• Íslenskan is a feminine noun form
• tungumálið is a neuter noun form

So both words are definite, but they take different article endings.

They are not exactly the same word, even though both refer to language.

• Íslenskan means the Icelandic language / Icelandic
• tungumálið means the language

So the sentence is structured like:

• Icelandic is beautiful, but the language is difficult.

The second part repeats the idea with a more general noun, which sounds natural and emphatic. It is similar to English saying:

• Icelandic is beautiful, but the language is difficult instead of
• Icelandic is beautiful, but it is difficult

Both are possible in English, and Icelandic also often allows this kind of repetition.

Because Icelandic adjectives must agree with the noun they describe.

That means the adjective changes form depending on:

• gender
• number
• case
• sometimes definiteness/strong vs. weak declension

In this sentence:

• Íslenskan is feminine singular
• tungumálið is neuter singular

So the adjective changes:

• falleg = feminine singular form of beautiful
• erfitt = neuter singular form of difficult

This kind of agreement is a major feature of Icelandic grammar.

Fallegt does mean beautiful, but it is the neuter singular form.

Compare:

• fallegur = masculine
• falleg = feminine
• fallegt = neuter

Since Íslenskan is feminine, the sentence needs falleg, not fallegt.

So:

• Íslenskan er falleg. = Icelandic is beautiful.
• Tungumálið er fallegt. = The language is beautiful.

The adjective must match the noun’s gender.

Because Icelandic usually repeats the verb to be in each clause, just as English does.

The sentence has two clauses:

• Íslenskan er falleg
• en tungumálið er erfitt

So er appears in both parts:

• er = is

This is completely normal and natural. Leaving out the second er would not be standard here.

En means but.

It connects two contrasting ideas:

• Íslenskan er falleg = Icelandic is beautiful
• en tungumálið er erfitt = but the language is difficult

So en is a very common coordinating conjunction, much like English but.

It is capitalized because it is the first word of the sentence, not because it is the name of a language.

In Icelandic, names of languages are usually not capitalized in the middle of a sentence.

So:

• Íslenskan er falleg. but
• Mér finnst íslenskan falleg.

That second example shows íslenskan in lowercase because it is no longer at the beginning.

This is different from English, where Icelandic is always capitalized.

They are in the nominative case, because they are the subjects of the clauses.

• Íslenskan = subject of er falleg
• tungumálið = subject of er erfitt

A basic pattern here is:

• [subject in nominative] + er + [adjective]

So this sentence is a good example of the nominative used for the subject of a statement.

Because the sentence joins two independent clauses with en (but), and Icelandic commonly uses a comma in this kind of structure.

So:

• Íslenskan er falleg, en tungumálið er erfitt.

This is similar to standard written English:

• Icelandic is beautiful, but the language is difficult.

The comma helps mark the contrast and separates the two full clauses clearly.

A rough English-friendly approximation is:

• Íslenskan er falleg ≈ EES-lens-kan er FAD-lek
• en tungumálið er erfitt ≈ en TUNG-gu-ma-lith er ER-fit

A few important points:

• Í is pronounced roughly like ee in see
• ll in falleg does not sound exactly like English ll; Icelandic has its own special pronunciation patterns
• ð in tungumálið is like the th in this
• á is usually like ow in now, though exact pronunciation depends on the word
• stress is usually on the first syllable in Icelandic words

A more careful learner pronunciation would be better than a purely English one, but these approximations can help you get started.

Sometimes yes, but it changes the feel and usage.

• Íslenskan er falleg is the most natural way to say Icelandic is beautiful when talking about the language as a specific known thing.
• Íslenska er falleg can occur, but it may sound less natural in this exact general statement, depending on context.

In Icelandic, language names are often used with the suffixed definite article when talking about the language itself in a general sense:

• Íslenskan
• ensku in other constructions
• etc.

So for this sentence, Íslenskan er falleg is the form learners should remember.

Grammatically, erfitt describes tungumálið.

So literally:

• the language is difficult

Of course, the intended meaning is usually that the language is difficult to learn / to use / to master, but Icelandic expresses that idea simply by saying the language itself is difficult.

English does exactly the same thing:

• The language is difficult.

So the grammar is straightforward even if the real-world meaning is broader.