Мне больше нравится гулять в парке вечером.

Because the verb нравиться works differently from English to like.

In Russian, the thing that is liked is the grammatical subject, and the person who likes it is put in the dative case.

So:

• Мне нравится гулять... = Walking ... is pleasing to me
• мне = to me

This is why Russian uses мне, not я.

Because гулять is the thing being liked, and it functions as the subject of нравится.

Russian нравиться agrees with what is pleasing:

• Мне нравится книга. = I like the book.
• Мне нравятся книги. = I like books.
• Мне нравится гулять. = I like walking.

Here, гулять is a single action/activity, so Russian uses singular нравится.

Here больше means more, as in more than something else.

So:

• Мне нравится гулять в парке вечером. = I like walking in the park in the evening.
• Мне больше нравится гулять в парке вечером. = I like walking in the park in the evening more / I prefer walking in the park in the evening.

It often implies a comparison, even if the second option is not stated.

Often, yes.

Мне больше нравится гулять в парке вечером can be translated naturally as:

• I prefer walking in the park in the evening
• I like walking in the park in the evening more

Russian does not always need to spell out the comparison with than. The listener may understand it from context.

If you want to make the comparison explicit, you can add чем:

• Мне больше нравится гулять в парке вечером, чем утром.
• I prefer walking in the park in the evening rather than in the morning.

Because Russian often uses the infinitive to talk about an activity in general.

So гулять here means to walk / walking as an activity.

Compare:

• Я люблю читать. = I like reading.
• Мне нравится плавать. = I like swimming.
• Мне больше нравится гулять... = I prefer walking...

English often uses -ing in these cases, but Russian commonly uses the infinitive.

Because в + prepositional case is used to mean in a place when talking about location.

• парк = park
• в парке = in the park

This is a location, not movement into the park.

Compare:

• Я гуляю в парке. = I am walking in the park.
• Я иду в парк. = I am going to the park.

So:

• в парк = into/to the park
• в парке = in the park

Russian often uses the instrumental case to express parts of the day when something happens:

• утром = in the morning
• днём = during the day / in the daytime
• вечером = in the evening
• ночью = at night

So вечером is a standard time expression meaning in the evening.

This is just the normal idiomatic form; learners usually memorize these as common adverb-like expressions.

A very literal breakdown would be:

• Мне = to me
• больше = more
• нравится = is pleasing / appeals
• гулять = to walk / walking
• в парке = in the park
• вечером = in the evening

So the sentence is roughly:

To me, walking in the park in the evening is more pleasing.

That sounds unnatural in English, but it helps explain the Russian grammar.

Yes, Russian word order is flexible.

The neutral order here is:

Мне больше нравится гулять в парке вечером.

But depending on emphasis, you could also say:

• Гулять в парке вечером мне больше нравится.
• Вечером мне больше нравится гулять в парке.

The basic meaning stays similar, but the focus changes:

• putting вечером earlier emphasizes in the evening
• putting гулять в парке вечером first emphasizes the activity itself

So Russian word order is often about emphasis, not just grammar.

Because the sentence is talking about the activity in general, not one completed walk.

гулять is the imperfective verb, and it is the normal choice for general enjoyment, habits, or repeated activities:

• Мне нравится читать.
• Мне нравится гулять.

A perfective form would sound wrong here because perfective verbs usually refer to a completed action, not an activity someone likes in general.

Yes, you can, and it would sound natural.

But there is a small nuance:

• Мне больше нравится гулять... sounds a bit like I prefer / I find it more enjoyable
• Я больше люблю гулять... sounds more direct, more like I love / like doing this more

Both are possible, but нравится is extremely common when talking about liking activities.

No. Without больше, the sentence simply means:

• Мне нравится гулять в парке вечером.
• I like walking in the park in the evening.

With больше, it adds comparison or preference:

• Мне больше нравится гулять в парке вечером.
• I prefer walking in the park in the evening.

So больше is what turns simple liking into liking more / preferring.