Der Flohmarkt beginnt morgen.

Because Flohmarkt is a masculine noun in German, so its nominative singular article is der.

In this sentence, der Flohmarkt is the subject, so the nominative article is used:

• der Flohmarkt = the flea market

German noun gender is something you usually have to learn together with the noun:

• der Flohmarkt
• not just Flohmarkt

It is in the nominative case because it is the subject of the sentence — the thing that is doing the action.

In Der Flohmarkt beginnt morgen, the flea market is the thing that begins, so it is the subject.

A good basic pattern is:

• subject + verb + time expression

So here:

• Der Flohmarkt = subject
• beginnt = verb
• morgen = time expression

The base form is beginnen, which means to begin.

beginnt is the 3rd person singular present tense form, used with er/sie/es and also with singular nouns like der Flohmarkt.

Conjugation:

• ich beginne
• du beginnst
• er/sie/es beginnt
• wir beginnen
• ihr beginnt
• sie/Sie beginnen

So der Flohmarkt beginnt works the same way as er beginnt.

Because standard German main clauses usually follow the verb-second rule.

That means the finite verb goes in the second position of the sentence.

In this sentence:

• Der Flohmarkt = first element
• beginnt = second element
• morgen = rest of the sentence

So the structure is:

• Der Flohmarkt | beginnt | morgen

Even if you move another element to the front, the verb still stays second:

• Morgen beginnt der Flohmarkt.

That is also correct.

Yes, absolutely. Morgen beginnt der Flohmarkt is correct.

Both sentences are natural:

• Der Flohmarkt beginnt morgen.
• Morgen beginnt der Flohmarkt.

The difference is mainly emphasis:

• Der Flohmarkt beginnt morgen puts the subject first.
• Morgen beginnt der Flohmarkt highlights morgen a bit more.

In both cases, the verb beginnt stays in second position.

In this sentence, morgen means tomorrow.

This is a very common point of confusion:

• morgen = tomorrow
• der Morgen = the morning

German capitalizes nouns, so capitalization helps:

• lowercase morgen = tomorrow
• capitalized Morgen = morning, when it is a noun

Examples:

• Ich komme morgen. = I’m coming tomorrow.
• Der Morgen ist kalt. = The morning is cold.

So in Der Flohmarkt beginnt morgen, morgen is an adverb meaning tomorrow.

Because here morgen is not a noun. It is being used as an adverb meaning tomorrow.

German capitalizes nouns, but not normal adverbs.

Compare:

• morgen = tomorrow → not capitalized
• der Morgen = the morning → capitalized because it is a noun

So the lowercase spelling tells you it is functioning as an adverb in this sentence.

Yes. You could also say:

• Der Flohmarkt fängt morgen an.

That means the same thing: The flea market starts tomorrow.

Both beginnen and anfangen are common, but there is a grammatical difference:

• beginnen is a single verb:
  
  • Der Flohmarkt beginnt morgen.
• anfangen is a separable verb in main clauses:
  
  • Der Flohmarkt fängt morgen an.

So an moves to the end in a normal main clause.

You would put the verb first:

• Beginnt der Flohmarkt morgen?

That is the normal way to form a yes/no question in German.

Statement:

• Der Flohmarkt beginnt morgen.

Question:

• Beginnt der Flohmarkt morgen?

So German often forms yes/no questions by switching from subject + verb to verb + subject.

Yes, the simple present is very normal in German for this idea.

German often uses the present tense where English might use either:

• begins tomorrow
• is beginning tomorrow
• starts tomorrow

So Der Flohmarkt beginnt morgen is a perfectly natural way to express a future event.

German frequently uses:

• present tense + time word

to talk about the future, especially when the time is already clear from a word like morgen.

Yes. Flohmarkt is a compound noun, which is very common in German.

It is made from:

• Floh = flea
• Markt = market

German often combines nouns into one word rather than writing them separately.

Other examples:

• Supermarkt
• Bahnhof
• Fußballspiel

So Flohmarkt being one word is completely normal German spelling.

A rough English-friendly guide would be:

• beginnt ≈ buh-GINT

A few useful pronunciation notes:

• the g in beginnt is a hard g
• the nn is just a normal doubled n
• the final t is clearly pronounced

Very roughly:

• be- sounds like a short unstressed buh
• ginnt rhymes roughly with mint, but with a hard g at the start

If you want the whole sentence roughly:

• Der Flohmarkt beginnt morgen
  ≈ dare FLOH-markt buh-GINT MOR-ghen

That is only approximate, but it can help you get started.