Мне нравится свежесть воздуха после дождя.

Because нравиться works differently from English to like.

In Russian, the structure is closer to:

• Мне нравится X = X is pleasing to me

So:

• мне is dative case of я and means to me
• нравится means is pleasing / pleases
• the thing that is liked is the grammatical subject

That is why я нравится is incorrect here.

Because the subject is свежесть (freshness), and that noun is singular.

Russian verbs agree with the grammatical subject, not with the person who feels the liking.

So in this sentence:

• свежесть = subject
• нравится = singular, because свежесть is singular

Compare:

• Мне нравится свежесть воздуха. = I like the freshness of the air.
• Мне нравятся цветы. = I like flowers.

In the second example, цветы is plural, so the verb becomes нравятся.

Свежесть is in the nominative case because it is the grammatical subject of the sentence.

Even though in English I feels like the subject in I like..., in Russian with нравиться, the thing that is liked becomes the subject.

So:

• мне = dative, experiencer
• свежесть = nominative, subject

Because воздуха is in the genitive case after свежесть.

The phrase свежесть воздуха means:

• the freshness of the air

This is a very common Russian pattern:

• чашка чая = a cup of tea
• цвет дома = the color of the house
• свежесть воздуха = the freshness of the air

So воздуха is genitive because it depends on the noun свежесть.

Because the preposition после always takes the genitive case.

So:

• дождь = nominative
• дождя = genitive

That is why:

• после дождя = after the rain

This is simply a case rule that has to be learned with the preposition после.

Свежесть is an abstract noun meaning freshness.

It comes from the adjective:

• свежий = fresh

So:

• свежий воздух = fresh air
• свежесть воздуха = the freshness of the air

The sentence focuses not just on the air itself, but on the quality or sensation of its freshness.

Yes. That would also be natural, but it means something slightly different.

• Мне нравится свежесть воздуха после дождя. = I like the freshness of the air after the rain.
• Мне нравится свежий воздух после дождя. = I like the fresh air after the rain.

The first sentence emphasizes the abstract quality freshness. The second emphasizes the actual air.

Both are correct; the nuance is just a little different.

Because Russian has no articles like a/an/the.

Whether something is definite or indefinite is usually understood from context.

So:

• свежесть воздуха can mean freshness of the air
• or in another context simply freshness of air

In this sentence, English naturally uses the, but Russian does not need any separate word for it.

Yes, Russian word order is fairly flexible.

The neutral order here is:

• Мне нравится свежесть воздуха после дождя.

But other orders are possible for emphasis, for example:

• Свежесть воздуха после дождя мне нравится.
• После дождя мне нравится свежесть воздуха.

These all express basically the same idea, but the focus changes slightly.

For learners, the original order is the safest and most natural starting point.

Not exactly.

• мне нравится = I like / it pleases me
• я люблю = I love / I really like

So:

• Мне нравится свежесть воздуха после дождя sounds natural and moderate: you enjoy it, you find it pleasant.
• Я люблю свежесть воздуха после дождя is stronger: you love it.

Both can be correct, but нравится is often the more neutral choice.

Then нравится would usually become нравятся.

For example:

• Мне нравится свежесть воздуха. = I like the freshness of the air.
• Мне нравятся запах и свежесть воздуха после дождя. = I like the smell and freshness of the air after the rain.

However, agreement with multiple nouns can get more complex depending on structure and style. The key beginner rule is:

• singular thing liked → нравится
• plural things liked → нравятся

The main word stress is:

• мне
• нрАвится
• свЕжесть
• вОздуха
• пОсле
• дождЯ

So roughly:

MNYE NRA-vi-tsa SVYE-zhest' VOZ-doo-kha POS-lye dazh-DYA

A few notes:

• мне begins with a soft mn sound
• нравится is often pronounced a bit more smoothly in fast speech
• дождя has stress on the last syllable

The dictionary forms are:

• я = I
• нравиться = to be pleasing, to appeal
• свежесть = freshness
• воздух = air
• после = after
• дождь = rain

In the sentence, some words appear in changed forms because of case:

• мне ← я
• воздуха ← воздух
• дождя ← дождь