Ich habe heute keine Fragen.

Habe is the 1st person singular present-tense form of haben (to have).

• ich habe = I have
• du hast = you have
• er/sie/es hat = he/she/it has

So Ich habe heute keine Fragen starts with I have ...

German uses haben just like English in this kind of sentence: to have questions = Fragen haben.

Because German usually uses kein to negate a noun.

Here, Fragen is a noun, and there is no other article before it, so German uses keine:

• Ich habe Fragen. = I have questions.
• Ich habe keine Fragen. = I have no questions / I don’t have any questions.

Use nicht for verbs, adjectives, adverbs, or when you are negating something other than a noun:

• Ich frage nicht. = I am not asking.
• Heute nicht. = Not today.

So in this sentence, keine is the natural choice.

Because kein changes its ending depending on gender, number, and case, similar to ein-words.

Here, Fragen is:

• plural
• accusative (because it is the direct object of habe)

The plural nominative/accusative form is keine:

• keine Frage = no question
• keine Fragen = no questions

So keine Fragen is the correct plural form here.

It is in the accusative case because it is the direct object of haben.

In Ich habe heute keine Fragen:

• Ich = subject
• habe = verb
• keine Fragen = direct object

With plural nouns like Fragen, the noun form often looks the same in nominative and accusative, so the case is mostly shown by the article-like word keine and by the sentence structure.

Plural is the most natural choice here.

Ich habe heute keine Fragen means something like:

• I have no questions today.
• I don’t have any questions today.

That is the normal way to say it.

Ich habe heute keine Frage is grammatically possible, but it sounds more specific, as if only one question was expected. In most everyday situations, German prefers the plural here.

So as a general sentence, keine Fragen is what you would normally say.

Because German main clauses usually follow the verb-second rule: the finite verb comes in the second position.

Here the structure is:

• Ich = position 1
• habe = position 2
• heute keine Fragen = the rest of the sentence

So Ich habe heute keine Fragen is perfectly normal.

Time words like heute often appear in the middle part of the sentence, after the verb.

Yes, absolutely.

Both are correct:

• Ich habe heute keine Fragen.
• Heute habe ich keine Fragen.

The difference is mainly emphasis:

• Ich habe heute keine Fragen. = neutral statement
• Heute habe ich keine Fragen. = puts more focus on today

When heute comes first, the verb still has to stay in second position, so it becomes:

• Heute habe ich ...

not Heute ich habe ...

Because all German nouns are capitalized.

• Frage = question
• Fragen = questions

So even in the middle of a sentence, nouns begin with a capital letter:

• Ich habe eine Frage.
• Ich habe keine Fragen.

This is one of the most noticeable spelling rules in German.

Yes. Fragen haben is completely natural and very common.

Examples:

• Hast du Fragen? = Do you have questions?
• Ich habe noch eine Frage. = I still have one question.
• Wir haben keine Fragen. = We have no questions.

German also uses eine Frage stellen for to ask a question, but that is a different idea:

• Ich habe eine Frage. = I have a question.
• Ich stelle eine Frage. = I ask a question.

So in your sentence, habe is exactly right.

A simple learner-friendly guide:

• ich ≈ ikh, but with a soft sound at the end, not a hard k
• heute ≈ HOY-tuh
• keine ≈ KY-nuh
• Fragen ≈ FRAH-gen

A few details:

• The ch in ich is the soft ich-Laut: [ɪç]
• eu in heute sounds like oy
• The g in Fragen is a normal hard g
• The final -e in heute and keine is usually a soft uh sound

So the whole sentence sounds roughly like:

ikh HAH-buh HOY-tuh KY-nuh FRAH-gen

Usually, no.

German normally requires the subject pronoun to be stated:

• Ich habe heute keine Fragen.

Leaving out ich would sound incomplete in a normal sentence.

German is not like Spanish or Italian, where the subject pronoun is often omitted. In standard German, you usually say it explicitly.