Ég nota þetta sjampó á morgnana, því hárið mitt verður mjúkara af því.

Because sjampó is neuter singular here, and it is the direct object of nota (to use).

• þessi changes form for gender, number, and case.
• The neuter singular nominative/accusative form is þetta.
• Since ég nota ... takes a direct object in the accusative, we get þetta sjampó.

So:

• þessi = this
• þetta = this (for a neuter singular noun in nominative/accusative)

Yes, it matters because Icelandic words affect the form of words around them.

Here, sjampó is treated as a neuter noun, so the demonstrative becomes þetta.

Even if a learner does not yet know the full declension of sjampó, the important thing in this sentence is:

• sjampó is neuter singular
• therefore: þetta sjampó

That is why you do not see þennan or þessa.

Á morgnana means in the mornings.

Literally, it is something like on the mornings, but English uses in the mornings, so that is the natural translation.

It is plural because the sentence describes a habitual action, something that happens regularly, not just on one morning.

Compare the idea:

• á morgnana = in the mornings, mornings in general
• á morgun = tomorrow
• á morgnana is an idiomatic time expression you will hear often

So the plural helps express routine or repeated time.

It is accusative plural with the definite article.

The noun is morgunn (morning), and in this expression Icelandic uses:

• á + accusative in this kind of time phrase
• morgnana = the mornings

So á morgnana is an established expression meaning in the mornings.

You do not need to translate the article literally as the every time; the whole phrase functions adverbially.

They look the same, but they are doing different jobs.

1. The first því

In ..., því hárið mitt verður mjúkara ...

this því is a conjunction meaning because / since.

So here it links the reason:

• I use this shampoo in the mornings, because ...

2. The second því

In af því

this því is a pronoun meaning it / that in the dative, because the preposition af requires the dative.

So:

• first því = because
• second því = it/that after af

That repetition can be confusing at first, but they are not the same grammatical item in this sentence.

Here af því means something like:

• from it
• because of it
• by using it

In natural English, the whole clause is best understood as:

• because my hair gets softer from it
• or because it makes my hair softer

The preposition af often means from or off, and it takes the dative case, which is why the pronoun appears as því.

So this part is quite literal:

• af = from
• því = it/that (dative)

Because Icelandic very often puts the possessive after a definite noun:

• hárið mitt = my hair
• literally something like the hair my

This is especially common with things that are naturally associated with a person, such as:

• hárið mitt = my hair
• hendin mín = my hand
• bíllinn minn = my car

You can sometimes see forms like mitt hár, but hárið mitt is very natural and common here.

A useful rule of thumb:

• definite noun + possessive is extremely common in Icelandic

It is nominative singular, because it is the subject of verður.

The structure is:

• hárið mitt = subject
• verður mjúkara = becomes softer

So the sentence is saying:

• my hair becomes softer

Since hár is a neuter singular noun, anything agreeing with it in this clause will also show neuter singular forms where relevant.

Because verða means to become / get, not just to be.

That matters a lot here:

• er mjúkt = is soft
• verður mjúkara = becomes / gets softer

The sentence is talking about a change in condition caused by the shampoo, so verður is the right verb.

In English we often say:

• my hair gets softer which matches Icelandic hárið mitt verður mjúkara very well.

Mjúkara is the comparative form of the adjective, meaning softer.

It is comparative because the sentence is not just saying the hair is soft; it is saying the hair becomes softer.

It also agrees with hárið:

• hár is neuter singular
• so the adjective appears in the corresponding neuter singular comparative form: mjúkara

So:

• mjúkt = soft
• mjúkara = softer

This is a very common pattern after verða:

• verða + comparative adjective
• become/get + comparative adjective

Yes. Nota here is the present tense of að nota (to use), first person singular:

• ég nota = I use

In this sentence it describes a habitual action:

• I use this shampoo in the mornings

The time phrase á morgnana helps make the habitual meaning clear. So this is not just about what the speaker is doing right now; it is about what they regularly do.

Yes. Icelandic word order is fairly flexible, and that alternative is perfectly natural.

Both of these work:

• Ég nota þetta sjampó á morgnana ...
• Á morgnana nota ég þetta sjampó ...

When you move á morgnana to the front, the verb usually stays in the second position, so you get:

• Á morgnana nota ég ...

That is a normal Icelandic pattern often called verb-second word order.

So changing the order can shift the emphasis a little, but not the basic meaning.

Because því introduces a reason clause here, similar to because in English.

The comma helps separate:

• the main statement: Ég nota þetta sjampó á morgnana
• the explanation/reason: því hárið mitt verður mjúkara af því

Icelandic punctuation often uses commas to separate clauses like this. In English, comma use with because is more restricted, but Icelandic commonly writes the clause boundary clearly.

So the comma is mainly there to mark the sentence structure.