Min stavning blir bättre när jag läser varje bokstav långsamt.

Because stavning is an en-word in Swedish: en stavning.

For en-words, the possessive my is min:

• min bok
• min bil
• min stavning

For ett-words, it would be mitt:

• mitt hus
• mitt namn

So min stavning is correct because stavning has common gender, not neuter.

Stavning means spelling.

It refers to the way words are spelled, not handwriting. So:

• Min stavning blir bättre = My spelling gets better / is improving

A related verb is stava, which means to spell.

Blir means becomes / gets, so it shows change over time.

• Min stavning blir bättre = My spelling gets better / is improving
• Min stavning är bättre = My spelling is better

So blir bättre suggests improvement, not just a description of the current state.

Yes. Bättre is the comparative form of bra (good / well), and it is irregular.

The forms are:

• bra = good / well
• bättre = better
• bäst = best

So:

• Min stavning blir bättre = My spelling gets better

Also, comparative adjectives like bättre do not change for gender or number here. You use bättre no matter what noun it goes with.

När usually means when.

In this sentence, it introduces a time clause:

• när jag läser varje bokstav långsamt = when I read each letter slowly

It can describe something habitual or generally true:

• När jag tränar, mår jag bättre = When I exercise, I feel better

So here it means something like when / whenever.

Because när introduces a subordinate clause, and in Swedish subordinate clauses the normal order is:

subject + verb

So:

• när jag läser = correct
• när läser jag = not correct here

This is different from main-clause word order, where Swedish often puts the verb in second position.

For example:

• Jag läser långsamt. = main clause
• när jag läser långsamt = subordinate clause

That is a very common Swedish pattern to learn.

Because varje means each / every, and in Swedish it is followed by a singular noun.

So:

• varje bokstav = each letter / every letter

Not:

• varje bokstäver ❌

More examples:

• varje dag = every day
• varje vecka = every week
• varje elev = every student

So even though the meaning may feel plural in English, Swedish uses the singular after varje.

Because varje already acts as the determiner.

In Swedish, you normally do not add en or ett after varje:

• varje bokstav = correct
• varje en bokstav = incorrect

This works much like English:

• every letter, not every a letter

Because långsamt is an adverb here, meaning slowly.

The adjective is:

• långsam = slow

The adverb is:

• långsamt = slowly

In this sentence, it describes how the reading happens:

• jag läser ... långsamt = I read ... slowly

It is not describing the noun bokstav; it is describing the verb läser.

Compare:

• en långsam elev = a slow student
• eleven läser långsamt = the student reads slowly

Läser is the present tense of läsa (to read).

The basic forms are:

• läsa = to read
• läser = read / am reading / do read
• läste = read (past)
• läst = read (supine/past participle-related form)

In this sentence, the present tense expresses a general or repeated action:

• när jag läser varje bokstav långsamt = when I read each letter slowly

Yes. Bokstav means letter in the sense of an alphabet letter:

• A, B, C are bokstäver

So:

• varje bokstav = each letter

It does not mean a letter you send in the mail. That would be brev.

Yes. You can move the time clause to the beginning:

När jag läser varje bokstav långsamt blir min stavning bättre.

That is also correct.

But then Swedish main-clause word order changes: the verb comes before the subject in the main clause after the opening clause.

So compare:

• Min stavning blir bättre när jag läser varje bokstav långsamt.
• När jag läser varje bokstav långsamt blir min stavning bättre.

Both mean the same thing, but the second version puts more emphasis on the when I read each letter slowly part.