Ég endurtek það sem ég les, því þannig man ég stafsetninguna betur.

Because ég takes the 1st person singular form of the verb.

The verb is endurtaka = to repeat. In the present tense:

• ég endurtek = I repeat
• þú endurtekur = you repeat
• hann/hún/það endurtekur = he/she/it repeats

So endurtekur would go with þú or hann/hún/það, not with ég.

This verb is a bit irregular, so it does not behave like a completely regular -a verb.

Það sem means what in the sense of the thing that / that which.

So:

• Ég endurtek það sem ég les
  = I repeat what I read = more literally, I repeat that which I read

This is a very common Icelandic structure. English often uses just what, but Icelandic frequently uses það sem.

Compare:

• Þetta er það sem ég vil. = This is what I want.
• Ég geri það sem ég get. = I do what I can.

So in your sentence, það sem ég les is the object of endurtek.

Because les is the correct 1st person singular present tense form of lesa (to read).

• að lesa = to read
• ég les = I read
• þú lest = you read
• hann/hún/það les = he/she/it reads

So lesa is the infinitive, while les is the conjugated form needed after ég.

In this sentence, því is being used as a conjunction meaning because / since / for.

So:

• ..., því þannig man ég stafsetninguna betur. = ..., because that way I remember the spelling better.

This is a common written and spoken use.

Be aware that því can also appear in other roles in Icelandic, so learners sometimes find it confusing. But here it is simply introducing the reason.

This is because Icelandic follows a verb-second pattern in main clauses very often.

When something other than the subject comes first, the finite verb usually comes next.

So here:

• þannig = that way / in that way
• then the verb: man
• then the subject: ég

That gives:

• þannig man ég stafsetninguna betur

This is very natural Icelandic word order.

If you kept the subject first, you could say something like:

• ég man stafsetninguna betur þannig

but that would not sound as natural for this meaning. The original sentence emphasizes that way: that way, I remember...

Because man is the present-tense form of the verb muna (to remember).

This verb is irregular.

Useful forms:

• að muna = to remember
• ég man = I remember
• þú manst = you remember
• hann/hún man = he/she remembers

So in the sentence:

• ég man stafsetninguna betur = I remember the spelling better

For English speakers, this can feel surprising because the infinitive muna looks quite different from man.

Because this is the definite singular accusative form of stafsetning (spelling).

Base noun:

• stafsetning = spelling

Definite form:

• stafsetningin = the spelling

But here it is the object of man (remember), so it appears in the accusative:

• stafsetninguna = the spelling

So:

• ég man stafsetninguna = I remember the spelling

The ending may look long, but it is just the noun plus the definite ending in the correct case.

Because betur is the comparative form of vel.

• vel = well
• betur = better
• best = best

So:

• Ég man það vel. = I remember it well.
• Ég man það betur. = I remember it better.

In your sentence:

• man ég stafsetninguna betur = I remember the spelling better

The idea is that repeating helps the speaker remember spelling more effectively.

Þannig means like that, that way, in that way, or thus, depending on context.

Here it means:

• by doing it that way
• in that way
• that way

So the sentence means that repeating what one reads is the method, and þannig points back to that method.

A very literal sense would be:

• because in that way I remember the spelling better

Yes.

The structure is:

• Ég endurtek = I repeat
• það sem ég les = what I read

So the full first clause is:

• Ég endurtek það sem ég les = I repeat what I read

Everything from það sem to les functions together as the thing being repeated.

Because því introduces a new clause giving the reason, and Icelandic commonly uses a comma there.

The sentence has two main parts:

• Ég endurtek það sem ég les
• því þannig man ég stafsetninguna betur

So the comma helps separate:

1. the statement
2. the explanation or reason

This punctuation is normal and helpful for reading.

Yes, in many contexts you could say:

• Ég endurtek það sem ég les, af því að þannig man ég stafsetninguna betur.

That also means I repeat what I read because that way I remember the spelling better.

Compared with af því að, plain því can sound a bit more compact and sometimes slightly more formal or written, though both are common and natural.

It specifically means spelling or orthography, depending on context.

In everyday learning contexts:

• stafsetning = spelling

Examples:

• góð stafsetning = good spelling
• læra stafsetningu = learn spelling
• stafsetningarvilla = spelling mistake

So in your sentence, the idea is remembering the correct spelling of words better.

Yes. The present tense here naturally expresses a habit or usual practice:

• Ég endurtek það sem ég les = I repeat what I read / I tend to repeat what I read

And the second part explains why that habit exists:

• því þannig man ég stafsetninguna betur = because that way I remember the spelling better

So the whole sentence sounds like the speaker is describing a regular learning strategy.