Þessi trefill passar vel við úlpuna mína.

Þessi means this.

In this sentence, it matches trefill (scarf), which is:

• masculine
• singular
• nominative

So þessi trefill = this scarf.

The word þessi changes depending on gender, number, and case, so the form you use depends on the noun it goes with.

Trefill means scarf.

It is a masculine noun in Icelandic. In this sentence it appears in the nominative singular because it is the subject of the sentence:

• Þessi trefill = this scarf

That is why the demonstrative is þessi.

As a phrase, passa vel við means something like:

• go well with
• match well with
• suit

So:

• Þessi trefill passar vel við úlpuna mína. = This scarf goes well with my coat/jacket.

A useful thing to remember is that passa can have several meanings in Icelandic depending on context, including fit, suit, or match.

The preposition við is commonly used with passa when you mean match or go with.

So:

• passa við = to match / go with

In this sentence, the scarf is being compared with the coat/jacket, so við is the natural choice.

This is a very common learner question.

Úlpa is a feminine noun meaning coat, jacket, or often a warm outer coat.

Here it appears as úlpuna, which is:

• singular
• definite = the coat/jacket
• accusative

Why accusative? Because the preposition við normally takes the accusative in this kind of usage.

So:

• úlpan = the coat / the jacket in nominative
• úlpuna = the coat / the jacket in accusative

Since the phrase is við úlpuna mína, the accusative form is needed.

In Icelandic, possessives often come after the noun, especially when the noun is already definite.

So:

• úlpuna mína = my coat/jacket

This is a very natural Icelandic pattern.

The possessive adjective must agree with the noun in:

• gender
• number
• case

Since úlpuna is:

• feminine
• singular
• accusative

the possessive becomes mína.

Yes, but it is not the same structure.

• mín úlpa = my coat
• úlpan mín or úlpuna mína = my coat / the coat of mine, depending on case

Icelandic often prefers:

• possessive after the noun when the noun is definite

So in this sentence, úlpuna mína is the expected form.

Vel is an adverb meaning well.

It modifies passar, so:

• passar vel við = matches well with

Without vel, the sentence would still make sense:

• Þessi trefill passar við úlpuna mína. = This scarf matches my coat.

Adding vel makes it sound more natural and specific: it matches well.

The sentence follows a straightforward pattern:

• Þessi trefill = subject
• passar = verb
• vel = adverb
• við úlpuna mína = prepositional phrase

So the structure is roughly:

• Subject + Verb + Adverb + Prepositional phrase

This is a very normal Icelandic word order for a simple statement.

The letter þ is pronounced like th in English think.

So Þessi begins with that kind of sound, not a z or d sound.

A rough approximation is:

• Þessi ≈ THESS-i

with stress on the first syllable.

Not always exactly.

Úlpa often refers to a warm outer garment, and in many contexts it can be translated as:

• coat
• jacket
• sometimes specifically a thicker outdoor jacket

So the best English translation depends on context. In this sentence, coat or jacket could both work depending on what the learner has already been shown.