Hon såg på skärmen att mobilen inte började ladda.

Because the sentence is in the past tense.

• ser = sees / is seeing
• såg = saw

The verb se is irregular:

• infinitive: se
• present: ser
• past: såg
• supine: sett

So Hon såg means she saw.

På skärmen means on the screen.

Swedish often uses på with screens, displays, pages, and surfaces where information appears:

• på skärmen = on the screen
• på tv:n = on the TV
• på sidan = on the page

So the idea is that she noticed this information on the screen.

Because skärmen is the definite form: the screen.

With many Swedish nouns, the definite article is added as an ending:

• en skärm = a screen
• skärmen = the screen

So Swedish usually does not use a separate word for the in cases like this.

Here att means that and introduces a subordinate clause.

The sentence has two parts:

• Hon såg på skärmen = She saw on the screen
• att mobilen inte började ladda = that the phone did not start charging

So att links the two parts together.

Because this is a subordinate clause after att.

In Swedish main clauses, inte often comes after the finite verb:

• Hon började inte ladda.

But in many subordinate clauses, inte comes before the finite verb:

• ... att mobilen inte började ladda

This is a very common Swedish word-order pattern.

Because mobilen means the mobile phone / the phone, while en mobil means a mobile phone.

Here, the sentence is talking about a specific phone, so the definite form is used:

• en mobil = a phone
• mobilen = the phone

Yes. In everyday Swedish, mobil very commonly means mobile phone / cell phone.

So:

• en mobil = a mobile phone
• mobilen = the mobile phone / the phone

A longer form like mobiltelefon also exists, but mobil is extremely common in normal speech.

After börja, Swedish often uses the infinitive directly, without att:

• började ladda = started charging

You can sometimes hear or see började att, but började ladda is more natural and common in everyday Swedish.

So this structure is normal:

• börja + infinitive
• började ladda
• började läsa
• började springa

Here ladda means to charge.

This verb can have different meanings depending on context, such as load or charge, but with a phone or battery it means charge.

So:

• mobilen laddar = the phone is charging
• började ladda = started charging

Because började ladda means started charging, not was charging.

It focuses on the beginning of the charging process. The sentence says that she saw that the phone did not begin to charge.

That is slightly different from saying it was not charging, which could describe a general state. Here the emphasis is on the phone failing to start charging.

Some parts could move, but the current word order is natural because it clearly shows that on the screen belongs with saw.

• Hon såg på skärmen att mobilen inte började ladda.

This means she saw this information on the screen.

If you moved på skärmen to another place, the sentence might become less natural or slightly less clear. The original version is a good standard way to say it.

Here på skärmen is best understood as extra information about where she saw it: on the screen.

So the sense is not mainly she looked at the screen, but rather she saw, on the screen, that...

That distinction matters because:

• Hon såg på skärmen att ... = She saw on the screen that ...
• Hon tittade på skärmen. = She looked at the screen.

So in this sentence, på skärmen tells you where the information appeared.