Garðurinn er fullur af blómum.

The ending -inn is the definite article attached to the noun, so garðurinn means the garden.

• garður = garden
• garðurinn = the garden

In Icelandic, the is usually added to the end of the noun instead of being a separate word.

Garðurinn is in the nominative singular because it is the subject of the sentence.

In Garðurinn er fullur af blómum:

• Garðurinn = the thing being talked about
• er = is
• fullur af blómum = full of flowers

The subject of a basic sentence like this normally appears in the nominative.

The adjective fullur has to agree with the noun it describes.

Since garðurinn is:

• masculine
• singular
• nominative

the adjective must also be masculine singular nominative, which is fullur.

Compare:

• garðurinn → fullur
• a neuter singular noun would take fullt
• a feminine singular noun would take full

So this is normal adjective agreement in Icelandic.

Because the preposition af governs the dative case.

The noun blóm means flower. Its plural forms include:

• blóm = flowers, nominative/accusative plural
• blómum = flowers, dative plural

Since af requires the dative, you get:

• af blómum = of flowers / with flowers

So the form is not chosen by meaning alone; it is required by the preposition.

Because the sentence means the garden is full of flowers, not just one flower.

If you wanted to say full of a flower or full of one flower, that would be unusual in meaning, but grammatically you would use the singular dative:

• af blómi = of a flower

Here, af blómum is the natural way to say full of flowers.

Yes, very closely.

In this sentence:

• fullur = full
• af = the preposition used with it
• fullur af blómum = full of flowers

This is a common Icelandic pattern. After fullur, you often say what something is full of by using af + dative.

Because Icelandic usually expresses definiteness with a suffix, not a separate article before the noun.

So instead of:

• the garden

Icelandic typically says:

• garðurinn

This is one of the first big differences English speakers notice.

There is also a separate definite article form in some formal or special constructions, but in everyday sentences like this, the attached article is the normal choice.

You can, but it does not mean the same thing.

• Garðurinn er fullur af blómum = The garden is full of flowers
• Garður er fullur af blómum = A garden is full of flowers or Garden is full of flowers, which sounds incomplete or unnatural in most contexts

So if you mean a specific garden, garðurinn is the correct form.

Yes, but this sentence uses the most normal and straightforward order:

• Garðurinn = subject
• er = verb
• fullur af blómum = complement

So the pattern is basically:

• Subject + Verb + Description

That is the standard neutral word order in Icelandic, much like English in this kind of sentence.

Other word orders are possible in special contexts, especially in writing or for emphasis, but this version is the ordinary one learners should use first.

The letter ð is like the th in English this, not like the th in thing.

So garðurinn contains that voiced th sound.

A rough learner-friendly pronunciation might be something like:

• GAR-thur-inn

But that is only approximate. The real Icelandic sounds and stress are a bit different.

A few helpful points:

• stress usually falls on the first syllable
• ð is a soft voiced sound
• á, ó, and ú are long vowel letters with their own pronunciations

Er is the present tense of vera, the verb to be.

So:

• Garðurinn er fullur af blómum = The garden is full of flowers

This is just the normal present-tense linking verb, connecting the subject to a description.

A good way to break the sentence down is:

• garðurinn → look up garður
• er → look up vera
• fullur → look up fullur
• blómum → look up blóm
• af → look up af

This is especially important in Icelandic because many words appear in changed forms depending on case, number, gender, or tense.