I januari brukar jag skriva nya mål i min dagbok.

In Swedish, i is the normal preposition for months:

• i januari = in January
• i februari = in February

So I januari is the natural way to say in January.

Swedish uses different prepositions from English in some time expressions, so it is best to learn them as patterns:

• i januari = in January
• på måndag = on Monday
• klockan tre = at three o’clock

Month names in Swedish normally do not take an article. So you simply say:

• i januari
• i april
• i december

This is similar to English, where we also usually say in January, not in the January.

This is because Swedish follows the V2 rule in main clauses. That means the finite verb must come in the second position.

Here, I januari comes first, so the finite verb brukar must come second:

• I januari = first position
• brukar = second position
• jag = after the verb

So:

• I januari brukar jag skriva... = correct
• I januari jag brukar skriva... = incorrect

Compare:

• Jag brukar skriva nya mål i min dagbok i januari.
• I januari brukar jag skriva nya mål i min dagbok.

Both are grammatical, but when you move I januari to the front, the verb has to stay in second position.

Brukar means something like usually, tend to, or normally do.

So brukar skriva means:

• usually write
• tend to write

It describes a habit or something that happens regularly.

For example:

• Jag brukar läsa på kvällen. = I usually read in the evening.
• Hon brukar dricka kaffe. = She usually drinks coffee.

In your sentence, brukar shows that writing new goals in January is a usual habit.

After brukar, Swedish normally uses the infinitive without att.

So:

• brukar skriva = correct
• brukar att skriva = not standard here

This is just a grammar pattern you need to learn:

• Jag brukar läsa.
• Vi brukar gå dit.
• Han brukar träna på morgonen.

Many Swedish verbs do take att before another verb, but bruka is not one of them in this structure.

Because skriva is the infinitive, and after brukar Swedish uses the infinitive form.

Compare:

• Jag skriver. = I write / am writing
• Jag brukar skriva. = I usually write

So brukar is the conjugated verb in the sentence, and skriva stays in the infinitive.

Nya mål means new goals in a general sense, not a specific set already known to the listener.

• nya mål = new goals
• de nya målen = the new goals
• ett nytt mål = a new goal

In your sentence, the speaker is talking generally about writing down some new goals, so the indefinite plural nya mål is natural.

A few useful points:

• mål is an ett-word in the singular: ett mål
• the plural is also mål
• the adjective changes:
  • ett nytt mål = a new goal
  • nya mål = new goals

Yes, mål can mean several things depending on context. Common meanings include:

• goal as an aim or objective
• goal in sports
• sometimes meal in older or special contexts, though this is not the everyday meaning learners usually need

In this sentence, nya mål clearly means new goals/objectives, like personal goals for the new year.

Because dagbok is a common-gender noun in Swedish, not a neuter noun.

Swedish has two grammatical genders:

• en-words
• ett-words

Dagbok is an en-word:

• en dagbok
• min dagbok

If it were an ett-word, you would use mitt, but that is not the case here.

Compare:

• en bok → min bok
• en dagbok → min dagbok
• ett hus → mitt hus

Here i means in, and dagbok means diary/journal. So i min dagbok literally means in my diary.

It is the natural preposition because you write in a book, diary, notebook, etc.

Examples:

• i en bok = in a book
• i min anteckningsbok = in my notebook
• i min dagbok = in my diary

Yes, but the meaning changes slightly.

• I januari skriver jag nya mål i min dagbok.

  • This sounds more like a statement about what I do in January, possibly this January or as a general fact depending on context.

• I januari brukar jag skriva nya mål i min dagbok.

  • This clearly emphasizes habit: it is something I usually do.

So brukar is useful when you want to make the habitual meaning explicit.