Kan du förklara det här så tydligt som möjligt?

Because this is a question.

In Swedish, yes/no questions are usually formed by putting the verb first. So:

• Du kan förklara det här. = You can explain this.
• Kan du förklara det här? = Can you explain this?

This word order is very common in Swedish. English does something similar with can you..., do you..., are you..., so this part is actually quite familiar.

Kan is the present tense of kunna, which usually means can or to be able to.

So here:

• Kan du... = Can you...

It introduces a request. In everyday Swedish, Kan du... ? is a very normal way to ask someone to do something.

Because förklara is the infinitive, meaning to explain.

After a modal verb like kan, Swedish normally uses the infinitive without att:

• kan förklara = can explain
• vill läsa = want to read
• måste gå = must go

So:

• Kan du förklara... literally follows the pattern Can you explain...

Det här means this or this thing / this matter.

Swedish often uses:

• det här for this with a neuter idea or for something general
• den här for a common-gender noun
• det här for a neuter noun

In this sentence, det här is not followed by a noun, so it works like this on its own:

• Kan du förklara det här...? = Can you explain this...?

If there were a noun, the form would depend on the gender of that noun:

• den här boken = this book
• det här huset = this house

Yes, you can say detta, and it also means this.

So this is possible:

• Kan du förklara detta så tydligt som möjligt?

The difference is mostly about style:

• det här sounds very natural and common in everyday speech
• detta sounds a bit more formal, written, or official

A learner will hear det här much more often in normal conversation.

Because tydligt is being used as an adverb, not an adjective.

The adjective is:

• tydlig = clear

But when Swedish describes how something is done, it often uses the -t form as an adverb:

• tala tydligt = speak clearly
• förklara tydligt = explain clearly

So:

• så tydligt som möjligt = as clearly as possible

It is describing the verb förklara, not a noun.

This is a very common Swedish structure meaning as ... as possible.

Pattern:

• så + adverb/adjective + som möjligt

Examples:

• så snabbt som möjligt = as quickly as possible
• så snart som möjligt = as soon as possible
• så tydligt som möjligt = as clearly as possible

So in your sentence, the speaker is asking for the explanation to be maximally clear.

Möjligt means possible.

It comes from möjlig = possible, and here the -t form is used.

In the expression som möjligt, it is part of the fixed phrase as possible:

• så enkelt som möjligt = as simply as possible
• så billigt som möjligt = as cheaply as possible
• så tydligt som möjligt = as clearly as possible

Yes. It is natural, normal, and polite in everyday Swedish.

A few important points:

• du is the standard word for you in Swedish, even in many situations where other languages might use a more formal form
• Swedish generally does not rely on a formal you in the same way that some other European languages do

So Kan du förklara det här så tydligt som möjligt? is perfectly polite in most contexts.

If you want to sound a little softer or more indirect, you could say:

• Skulle du kunna förklara det här så tydligt som möjligt?

That feels a bit more like Could you explain this as clearly as possible?

It sounds natural.

A Swedish speaker could absolutely say:

• Kan du förklara det här så tydligt som möjligt?

It is clear, idiomatic, and useful in real life, especially in situations like:

• asking a teacher
• asking for instructions
• asking someone to simplify something difficult

Yes. Here are some natural alternatives with slightly different tone or style:

• Kan du förklara det här tydligare?
  = Can you explain this more clearly?

• Kan du förklara det här på ett tydligt sätt?
  = Can you explain this in a clear way?

• Skulle du kunna förklara det här så tydligt som möjligt?
  = Could you explain this as clearly as possible?

• Kan du förklara detta så tydligt som möjligt?
  = Same meaning, but detta is a bit more formal than det här

The original sentence is one of the most natural all-purpose versions.

A rough pronunciation guide could be:

kan dyu fur-KLA-ra de här so TYD-ligt som MÖJ-ligt

A few useful notes:

• du is often pronounced more like dyu than plain English doo
• förklara has stress on kla
• tydligt has stress on the first syllable
• möjligt has a vowel sound that does not exist exactly in English, so it may take practice

The rhythm is quite smooth, and in fast speech some words may sound slightly reduced, but the sentence is still easy to recognize.