Jag spärrade kortet efter stölden.

Here spärrade means blocked, froze, or cancelled a card so it can no longer be used. With bank cards, spärra kortet is the normal Swedish expression.

So in this sentence, it does not mean physically locking something. It means putting the card out of use.

Yes. Spärrade is the preterite (simple past) of spärra.

A few useful forms:

• spärra = to block / freeze
• spärrar = blocks / is blocking
• spärrade = blocked
• har spärrat = has/have blocked

So Jag spärrade kortet means I blocked the card or I froze the card.

Because kortet is the definite singular form: the card.

Swedish usually adds the definite article to the end of the noun:

• ett kort = a card
• kortet = the card

So:

• Jag spärrade kortet = I blocked the card

The noun kort is a neuter noun, which is why the definite ending is -et.

Swedish often leaves out my when it is already obvious from the context whose thing is meant.

So Jag spärrade kortet will often be understood as I blocked my card, especially in a situation like theft or loss.

You can also say:

• Jag spärrade mitt kort

That is also correct, but it can sound more explicit or emphatic.
In many everyday situations, kortet is enough.

Efter means after, and stölden means the theft.

So efter stölden means:

• after the theft
• following the theft

It refers to something that happened later in time than the theft.

Because stölden is the definite form: the theft.

Compare:

• en stöld = a theft
• stölden = the theft

The sentence is talking about a specific theft, not theft in general.

So:

• efter en stöld = after a theft
• efter stölden = after the theft

Yes. This is a very normal Swedish main-clause order:

• Jag = subject
• spärrade = verb
• kortet = object
• efter stölden = time expression

So it follows the common pattern:

Subject + verb + object + time phrase

You could also move the time phrase to the front:

• Efter stölden spärrade jag kortet.

That is also correct. In Swedish main clauses, the finite verb still stays in the second position.

Yes, very much so. It is the standard expression used for bank cards, credit cards, and similar things.

For example:

• Jag måste spärra mitt kort. = I have to block my card.
• Har du spärrat kortet? = Have you blocked the card?

A more literal English-based verb like blockera is usually not the most natural choice here. For cards, spärra is the idiomatic verb.

The basic form is stöld, which means theft.

Useful forms:

• en stöld = a theft
• stölden = the theft
• stölder = thefts
• stölderna = the thefts

So stölden is just stöld with the definite ending -en.

Not exactly. Stöld means theft.

That matters because English speakers sometimes mix up theft, robbery, and burglary.

In Swedish:

• stöld = theft
• rån = robbery
• inbrott = burglary / break-in

So efter stölden specifically means after the theft, not necessarily after the robbery.

In the present tense, it would be:

• Jag spärrar kortet efter stölden.

That means I am blocking / I block the card after the theft.

But in real-life context, the past tense spärrade is often more natural if the action is already completed.