Ég ætla að láta snyrta hárið mitt á morgun.

Ætla að is a very common Icelandic pattern meaning to intend to, to be going to, or to plan to do something.

In this sentence:

• Ég ætla að ... = I’m going to / I intend to ...

Grammatically:

• ætla is the conjugated verb
• að introduces the following infinitive phrase

So Ég ætla að láta... literally means something like I intend to have... done.

Here láta is being used in a causative way. That means it shows that the subject causes something to happen, usually by having someone else do it.

So:

• láta snyrta hárið mitt = have my hair trimmed/cut
• not trim my hair myself

This is very similar to English have/get something done:

• I’m going to have my hair cut
• Ég ætla að láta snyrta hárið mitt

Depending on context, láta can also mean let, make, or have, but in this sentence the best idea is have something done.

Because after láta in this kind of construction, the next verb normally stays in the infinitive.

So the structure is:

• láta + infinitive

Examples:

• láta gera það = have that done
• láta laga bílinn = have the car repaired
• láta snyrta hárið mitt = have my hair trimmed

So snyrta is not conjugated because láta is already the main finite verb in that part of the sentence.

Not exactly. Snyrta has the sense of tidy, neaten, trim, or groom.

With hair, it often suggests:

• trimming
• tidying up
• making it neat

It can overlap with the idea of getting a haircut, but it is a bit broader and often softer than a straight cut.

A learner may also see:

• klippa hárið = cut the hair
• snyrta hárið = trim/tidy the hair

In real life, both can be used depending on the situation.

In Icelandic, when a noun is definite and has a possessive like my, the normal order is:

• noun + definite article + possessive

So:

• hárið mitt = my hair

This is the usual pattern.

Why?

• hár = hair
• hárið = the hair
• hárið mitt = my hair

The form mitt hárið is not the normal way to say it.

You may also sometimes see mitt hár, but that is a different structure and is less neutral in everyday usage. The most natural form here is hárið mitt.

Because hár is a neuter singular noun, and the possessive must agree with it in gender, number, and case.

The possessive forms of minn are:

• minn for masculine
• mín for feminine
• mitt for neuter

Since hár is neuter:

• hárið mitt = my hair

So mitt is used because it matches hár.

Yes, it is functioning as the direct object of the action snyrta.

In other words, the hair is the thing being trimmed.

So the object is:

• hárið mitt

For many neuter nouns in Icelandic, the nominative and accusative singular look the same. That is why hárið does not visibly change here.

So even though it is accusative in function, its form is still hárið.

Because the subject is ég = I.

In Icelandic, sinn / sín / sitt is a reflexive possessive, but it is mainly used with third-person subjects:

• Hún snyrtir hárið sitt = She trims her own hair

But with first person, you use the normal possessive:

• Ég snyrti hárið mitt = I trim my hair

So in your sentence:

• Ég ætla að láta snyrta hárið mitt is correct

not ... hárið sitt, because the subject is I, not he/she/they.

Á morgun means tomorrow.

It is a fixed adverbial expression. Even though á often means on, you should learn á morgun as a whole phrase meaning simply:

• tomorrow

So:

• Ég ætla að láta snyrta hárið mitt á morgun.
• I’m going to have my hair trimmed tomorrow.

Yes. Icelandic word order is flexible, especially with time expressions.

These are both natural:

• Ég ætla að láta snyrta hárið mitt á morgun.
• Á morgun ætla ég að láta snyrta hárið mitt.

When you move á morgun to the front, the verb comes before the subject in the main clause:

• Á morgun ætla ég...

That is a normal Icelandic word-order rule.

Yes, it is natural and grammatical, especially if you want to emphasize the causative idea: you are arranging for someone to do it.

A native speaker might also use other everyday expressions, for example:

• Ég ætla í klippingu á morgun. = I’m going for a haircut tomorrow.
• Ég ætla að fara í klippingu á morgun. = I’m going to go get a haircut tomorrow.

But Ég ætla að láta snyrta hárið mitt á morgun is still a good, clear sentence and very useful for learning how láta + infinitive works.