Wie viel Zeit hast du heute?

In modern standard German, wie viel is normally written as two words when it means how much or how many.

So:

• Wie viel Zeit hast du heute? = correct and preferred

You may still sometimes see wieviel, especially in older texts or less formal writing, but wie viel is the standard form learners should use.

Because Zeit is a noun, and all nouns are capitalized in German.

Examples:

• die Zeit = time
• der Tag = day
• das Buch = book

So even in the middle of a sentence, Zeit must begin with a capital letter.

Because this is a question with a question word.

German word order here is:

1. question word or phrase
2. conjugated verb
3. subject
4. the rest of the sentence

So:

• Wie viel Zeit = question phrase
• hast = conjugated verb
• du = subject
• heute = time expression

That is why German says:

• Wie viel Zeit hast du heute?

and not:

• Wie viel Zeit du hast heute? in a normal direct question

Zeit is in the accusative case.

That is because haben usually takes a direct object, and the thing being had is the direct object:

• du = subject
• hast = verb
• Zeit = direct object

So in this sentence, Zeit is the thing the person has.

A useful detail: Zeit is a feminine noun, but here there is no article, so you do not see any obvious case ending. The form Zeit looks the same here.

Because Zeit is being treated as an uncountable noun here, like time in English.

German uses:

• wie viel with uncountable nouns or when asking about quantity in general
• wie viele with plural countable nouns

So:

• Wie viel Zeit ...? = How much time ...?
• Wie viele Bücher ...? = How many books ...?

You would not say wie viele Zeit, because Zeit is not being counted as separate items.

Yes. du is the informal singular form of you.

So this sentence sounds like you are speaking to:

• a friend
• a family member
• a child
• someone you know well

If you want to be formal, use Sie:

• Wie viel Zeit haben Sie heute?

Notice that the verb changes too:

• du hast
• Sie haben

No, but the end is a very natural place for it in this sentence.

• Wie viel Zeit hast du heute? = very natural
• Wie viel Zeit hast du heute denn? = possible, with a slightly conversational tone
• Wie viel Zeit hast du denn heute? = also very natural

German often allows some flexibility with time expressions like heute, but in a simple sentence like this, putting it near the end is the easiest and most natural choice.

Yes. Zeit haben is a very common German expression meaning to have time or to be available.

So this sentence is not about owning time in a literal sense. It means something like:

• how much free time do you have?
• how much time is available to you today?

Related examples:

• Hast du Zeit? = Do you have time?
• Ich habe keine Zeit. = I do not have time.

A simple pronunciation guide is:

vee feel tsite hahst doo HOY-tuh

A more precise breakdown:

• wie sounds like vee
• viel sounds like feel
• Zeit sounds roughly like tsite
• hast has a clear h
• du sounds like doo
• heute sounds like HOY-tuh

A rough IPA version is:

/viː fiːl tsaɪt hast duː ˈhɔʏtə/

One important point for English speakers:

• German w sounds like English v
• German v in viel sounds like English f

Yes. If the context already makes the time clear, you can simply say:

• Wie viel Zeit hast du?

That means How much time do you have?

Adding heute makes it specific to today:

• Wie viel Zeit hast du heute?

So heute is not grammatically required, but it adds important information.

Normally it asks about available time, not the current time on a clock.

So it usually means:

• how much time can you spend on something today?
• how free are you today?

If you wanted to ask for the current time, you would say something completely different:

• Wie spät ist es? = What time is it?

So Wie viel Zeit hast du heute? is about availability or time to do something.