syukuzitu no kouen ha nigiyaka desu ga, heizitu no asa ha sorehodo hito ga ooku arimasen.

の connects nouns and shows a relationship between them.

• 祝日の公園 = the park on a holiday
• 平日の朝 = a weekday morning / the morning on a weekday

In English, we often use of, on, or just put nouns together. In Japanese, の is very commonly used for this kind of connection.

So here:

• 祝日 の 公園 = the park on a holiday
• 平日 の 朝 = the morning of a weekday / a weekday morning

The exact English translation depends on context, but the grammar is simply noun + の + noun.

にぎやか is a na-adjective. Na-adjectives do not conjugate like i-adjectives.

So in a polite sentence:

• にぎやかです = is lively / is bustling

You do not say にぎやかいです, because にぎやか is not an i-adjective.

Compare:

• にぎやかです = lively
• 静かです = quiet
• 便利です = convenient

These all behave like na-adjectives.

は marks the topic of the sentence.

• 祝日の公園は = as for the park on holidays
• 平日の朝は = as for weekday mornings

The sentence is comparing two situations:

1. the park on holidays
2. weekday mornings

Using は helps create that contrast. It sets up each side as a topic and makes the comparison feel natural.

Here, が means but.

So:

• にぎやかですが = is lively, but...

This が connects two contrasting ideas:

• On holidays, the park is lively,
• but
• on weekday mornings, there are not that many people.

This is different from が as a subject marker. Japanese が has more than one use, and here it is a conjunction-like particle meaning but.

Because 多い describes the quantity of something, and that something is 人.

• 人が多い = there are many people / people are numerous

In Japanese, 多い usually takes a noun with が:

• 車が多い = there are many cars
• 店が多い = there are many shops
• 人が多い = there are many people

So 人が多くありません means:

• there are not many people

Without 人, the sentence would be less clear unless the noun was already strongly understood from context.

In 人が多くありません, が marks 人 as the thing whose quantity is being described.

• 人が多い is the standard pattern for there are many people

If you said 人は多くありません, it would sound more contrastive, like:

• As for people, there aren't many possibly implying contrast with something else.

So 人が is the more neutral and natural choice here.

多い is an i-adjective. Its polite negative form is made like this:

• 多い
• remove い → 多く
• add ありません
• 多くありません

So:

• 多いです = is many / are many
• 多くありません = is not many / are not many

This is a standard polite negative pattern for i-adjectives.

You may also see:

• 多くないです
• 多くありません

Both mean the same thing, but 多くありません is a bit more formal or textbook-like.

それほど means that much or to that extent.

It is often used with a negative:

• それほど〜ない = not that ... / not so ...

So:

• それほど人が多くありません = there are not that many people

This softens the statement a little. It does not mean almost nobody is there. It means the number of people is not especially large.

Compare:

• 人が多くありません = there are not many people
• それほど人が多くありません = there are not that many people

The second one sounds a bit more nuanced and less absolute.

Yes, you can think of it that way.

The first half says:

• 祝日の公園は = as for the park on holidays

The second half says:

• 平日の朝は = as for weekday mornings

A natural English learner question is: weekday mornings where?

The answer is that Japanese often omits repeated information when it is understood from context. So the second half implies:

• 平日の朝の公園は = as for the park on weekday mornings

But Japanese does not need to repeat 公園 because it is already clear that the sentence is still talking about the park.

The second は helps mark a new contrasting topic.

The sentence structure is basically:

• On holidays, as for the park, it is lively, but...
• as for weekday mornings, there are not that many people.

Repeating は makes the contrast clearer:

• 祝日の公園は ... が、平日の朝は ...

This is very common in Japanese when comparing two cases:

• 夏は暑いですが、冬は寒いです。
• この店は安いですが、あの店は高いです。

Not in exactly the same place.

This sentence uses:

• にぎやかです
  • が

That pattern means:

• It is lively, but...

If you wanted to use でも, you would normally start a new sentence or clause in a different way.

For example:

• 祝日の公園はにぎやかです。でも、平日の朝はそれほど人が多くありません。

That is also natural, but it is slightly more conversational and split into two sentences.

So:

• が = smoother connection within one sentence
• でも = more like However, ... at the start of the next statement

Sometimes yes, but they are not exactly the same.

• にぎやか means lively, bustling, full of activity
• 人が多い means there are many people

A place can be:

• にぎやか because it feels energetic and active
• 人が多い because the number of people is large

They often overlap, but the nuance is different:

• にぎやか focuses on the atmosphere
• 人が多い focuses on the number of people

So this sentence nicely uses two different ideas:

• holidays: the park feels lively
• weekday mornings: there are not that many people

Because Japanese often avoids repeating information that is already obvious.

The full version could be:

• 祝日の公園はにぎやかですが、平日の朝の公園はそれほど人が多くありません。

That is grammatical, but it sounds a bit repetitive.

The shorter version:

• 祝日の公園はにぎやかですが、平日の朝はそれほど人が多くありません。

is more natural because the listener already knows the topic is still the park.

This kind of omission is very common in Japanese.