Hon brukar inte slarva, men i dag glömde hon både mobilen och plånboken.

Brukar is used to talk about something that usually happens or someone’s typical habit.

So Hon brukar inte slarva means something like:

• She doesn’t usually get careless
• She isn’t normally sloppy
• She doesn’t tend to be careless

A very common pattern is:

• brukar + infinitive

For example:

• Jag brukar läsa på kvällen = I usually read in the evening
• De brukar komma sent = They usually arrive late

In your sentence, slarva is the infinitive after brukar.

Because in a normal Swedish main clause, inte usually comes after the finite verb.

Here, the finite verb is brukar, so the order is:

• Hon brukar inte slarva

Structure:

• Hon = subject
• brukar = finite verb
• inte = negation
• slarva = infinitive

This is a very important Swedish word-order pattern.

Compare:

• Hon kommer inte = She is not coming
• Jag förstår inte = I do not understand
• Vi brukar inte äta där = We do not usually eat there

Slarva means to be careless, sloppy, or to do something without enough attention.

Depending on context, it can mean:

• being messy
• not being careful
• doing something carelessly
• neglecting details

So Hon brukar inte slarva suggests that she is normally careful and that forgetting things is unusual for her.

Examples:

• Du slarvar med läxorna = You are being sloppy with your homework
• Han slarvade bort nycklarna = He carelessly lost the keys

Because Swedish uses V2 word order in main clauses. That means the finite verb must come in the second position.

If the sentence begins with the time expression i dag, then the verb has to come next:

• I dag glömde hon både mobilen och plånboken

Structure:

1. I dag = first element
2. glömde = finite verb in second position
3. hon = subject after the verb

If you start with the subject instead, you can say:

• Hon glömde både mobilen och plånboken i dag

Both are possible, but the emphasis is a little different:

• I dag glömde hon ... puts more focus on today
• Hon glömde ... i dag starts more neutrally with she

Yes, both i dag and idag are accepted.

They mean the same thing: today.

You will see both spellings in real Swedish:

• i dag
• idag

There is no difference in meaning here. It is mostly a spelling/style choice.

This is another result of Swedish V2 word order.

When i dag comes first, the finite verb must still be in second position, so the subject moves after the verb:

• I dag glömde hon ...

If you kept hon before the verb, you would get:

• I dag hon glömde ...

and that is not correct in a normal main clause.

This is one of the biggest differences between Swedish and English. English can say:

• Today she forgot ...

But Swedish needs:

• I dag glömde hon ...

Både ... och means both ... and.

In the sentence:

• både mobilen och plånboken = both the phone and the wallet

It is used to link two things together and show that both of them are included.

More examples:

• Hon talar både svenska och engelska = She speaks both Swedish and English
• Vi åt både fisk och ris = We ate both fish and rice

So here the sentence stresses that she forgot not just one thing, but two.

Because Swedish often uses the definite form when talking about a specific, known item.

• mobilen = the phone
• plånboken = the wallet

In context, these clearly mean her phone and her wallet, even though Swedish does not explicitly say her here.

English often prefers a possessive:

• her phone
• her wallet

But Swedish can often use the definite form when it is obvious whose items are meant.

Compare:

• Hon tog mobilen = She took the phone
• Hon glömde plånboken = She forgot the wallet

In context, these often mean her phone and her wallet.

Glömde is the past tense of glömma, meaning to forget.

• glömma = to forget
• glömde = forgot

It is used because the sentence describes a completed event:

• today, she forgot her phone and wallet

This is the normal simple past form in Swedish narrative.

A few related forms:

• Jag glömmer = I forget / I am forgetting
• Jag glömde = I forgot
• Jag har glömt = I have forgotten

Here, glömde works naturally because the sentence is telling what happened earlier today.

Because Swedish normally needs an explicit subject in each clause.

The sentence has two coordinated clauses:

1. Hon brukar inte slarva
2. men i dag glömde hon både mobilen och plånboken

Even though the subject is the same person, Swedish still says hon again in the second clause.

English works the same way here:

• She doesn’t usually get careless, but today she forgot both her phone and wallet

So the repeated hon is completely normal.