Kan du tale langsommere, så jeg bedre forstår dig?

Because this is a yes/no question in Danish. In main-clause questions, the finite verb usually comes first, followed by the subject:

• Kan du ...? = Can you ...?

Compare:

• Du kan tale langsommere. = You can speak more slowly.
• Kan du tale langsommere? = Can you speak more slowly?

So the verb kan moves in front of du to form the question.

Yes. Kan is the present tense of kunne, and here it works like English can in a request:

• Kan du ...? = Can you ...?

In practice, this often functions as a polite request, not just a question about ability. So Kan du tale langsommere? is a normal way to ask someone to speak more slowly.

Because after a modal verb like kan, Danish normally uses the infinitive form of the next verb.

• kan tale = can speak

So:

• kan = finite/modal verb
• tale = infinitive

This is similar to English:

• can speak not
• can speaks

Tale means to speak, and snakke means to talk/chat. In many everyday situations, both can work.

So these are both natural:

• Kan du tale langsommere?
• Kan du snakke langsommere?

A rough nuance:

• tale can sound a little more neutral or slightly more formal
• snakke can sound a little more informal and conversational

In this sentence, either is fine.

Because langsommere means more slowly or slower, while langsomt means slowly.

Compare:

• Tal langsomt. = Speak slowly.
• Tal langsommere. = Speak more slowly / Speak slower.

So if the person is already speaking, and you want them to reduce their speed compared with how they are speaking now, langsommere is the natural choice.

Here så means so or so that.

• Kan du tale langsommere, så jeg bedre forstår dig?

The second part gives the reason or result:

• ... so that I understand you better

In natural English, this is often translated as so I can understand you better, even though Danish does not need an extra can there.

Both can be understood, but så jeg bedre forstår dig is very natural because after så you have a subordinate clause, and Danish subordinate clauses do not use the usual main-clause word order.

A key pattern is:

• in a main clause, the finite verb comes early
• in a subordinate clause, adverbs often come before the finite verb

So:

• jeg forstår dig bedre = main-clause style
• så jeg bedre forstår dig = subordinate-clause style

This is a very important Danish pattern. You will also see it after words like:

• fordi
• at
• når
• hvis

For example:

• Jeg ved, at han ikke kommer. not
• Jeg ved, at han kommer ikke.

Because bedre is an adverb here, and in a subordinate clause it usually comes before the finite verb.

So in:

• så jeg bedre forstår dig

the order is:

• jeg = subject
• bedre = adverb
• forstår = finite verb
• dig = object

This is one of the most useful word-order rules to notice in Danish.

Bedre means better.

Here it modifies the verb forstår:

• jeg forstår dig bedre = I understand you better

It does not mean that the understanding is perfect; it just means improved understanding.

Because dig is the object form of you, while du is the subject form.

Compare:

• Du taler. = You speak.
  
  • du = subject
• Jeg forstår dig. = I understand you.
  
  • dig = object

This is similar to English I/me, he/him, we/us, although English does not distinguish you in the same way.

Yes, it is polite and very normal.

• Kan du tale langsommere, så jeg bedre forstår dig?

It sounds like a reasonable everyday request. If you want to sound even softer or more polite, you could add something like:

• Kan du tale lidt langsommere ... = Can you speak a little more slowly ...
• Kan du måske tale langsommere ... = Could you maybe speak more slowly ...
• Vil du tale lidt langsommere? = Would you speak a little more slowly?

You can also add tak at the end in conversation.

Yes, but it means something different.

• Kan du tale langsommere? = Can you speak more slowly?
• Kan du gentage det? = Can you repeat that?

So if the problem is speed, use tale langsommere. If the problem is that you missed what was said, use gentage det. In real life, learners often use both:

• Kan du tale langsommere?
• Kan du gentage det?

In modern Danish, du is used in almost all situations, even polite ones. There used to be more formal usage historically, but today du is standard.

So in this sentence, du is completely normal and appropriate.

Forstår is the present tense of forstå, which means to understand.

• at forstå = to understand
• jeg forstår = I understand

Many Danish present-tense verbs end in -r, so:

• tale → taler
• forstå → forstår

But after kan, you use the infinitive:

• kan forstå
• kan tale

The sentence as given is already natural. In speech, many Danes might also say slightly simpler versions such as:

• Kan du tale lidt langsommere?
• Kan du snakke lidt langsommere?
• Kan du sige det lidt langsommere?

The original sentence is a bit fuller because it includes the reason:

• ... så jeg bedre forstår dig

That makes it clear and friendly, because you are explaining why you are asking.