Kan du lägga det där brevet i lådan?

Because this is a yes/no question in Swedish. In main-clause questions, the verb comes before the subject.

• Kan du ...? = Can you ...?
• Compare with a statement:
  • Du kan lägga det där brevet i lådan. = You can put that letter in the box.

So the word order changes because it is a question.

It can do both, just like English Can you ...?

In this sentence, it is very naturally understood as a request:

• Kan du lägga det där brevet i lådan? = Can you put that letter in the box?

Literally it is about ability, but in everyday use it often functions as a polite way to ask someone to do something.

Lägga means to lay or to put, especially when something is placed down, often in a flat position.

That is why it works well with brev because a letter is something you typically lay down.

Swedish often chooses different verbs depending on how something is placed:

• lägga for laying something down
• ställa for setting something upright
• sätta for putting something into a sitting/fixed position

So lägga brevet is very natural.

Because det där is the Swedish way to say that for a neuter singular noun.

Here:

• det där = that
• brevet = the letter

So together:

• det där brevet = that letter

By itself, där often means there, but in det där it is part of the demonstrative expression meaning that.

Because in Swedish, after det här / det där / den här / den där, the noun is normally in the definite form.

So Swedish says:

• det där brevet = that letter

not:

• det där brev

This is a very common Swedish pattern:

• den där boken = that book
• det här huset = this house
• de där breven = those letters

English does not do this, but Swedish does.

Because the base noun is ett brev.

That means brev is a neuter noun in Swedish. Neuter nouns usually take -et in the singular definite form.

So:

• ett brev = a letter
• brevet = the letter

That is why you see brevet here.

Because brev is a neuter noun, not a common-gender noun.

Swedish demonstratives agree with the noun’s gender:

• den där for en-words
• det där for ett-words

Examples:

• den där boken = that book
• det där brevet = that letter

So det där is correct because brev is an ett-word.

In Swedish, i can mean both in and into, depending on the context.

Here, the verb lägga already shows movement, so i lådan is understood as into the box or in the box as a result of the action.

So Swedish does not need a separate word exactly like English into in many cases.

Because it refers to a specific box/drawer that both speaker and listener can identify.

• en låda = a box / a drawer
• lådan = the box / the drawer

So i lådan means in the box or in the drawer, not just any random one.

Låda is an en-word.

So its forms are:

• en låda = a box / a drawer
• lådan = the box / the drawer

That is why the definite form ends in -n here.

Yes. Låda can mean several similar things depending on context, such as:

• box
• drawer
• sometimes other container-like meanings

So i lådan could mean in the box or in the drawer, depending on the situation.

Usually, yes. Det där often suggests that rather than this, so it can imply some distance, either physical or psychological.

Compare:

• det här brevet = this letter
• det där brevet = that letter

So det där points to something that is not as close to the speaker.

In modern Swedish, du is used in almost all situations, even many fairly formal ones.

So Kan du ...? is completely normal.

Swedish does not use formal and informal you the way some other European languages do. Very formal wording is possible in other ways, but du is standard.

The pattern stays very similar.

For example:

• de där breven = those letters

Compare:

• singular neuter: det där brevet
• plural: de där breven

So when you move from singular to plural, det där becomes de där, and the noun changes to its plural definite form.