Летом хлопок подходит мне больше, чем шёлк.

Летом is the normal Russian way to say in summer.

Here летом is an old instrumental-case form used adverbially for time. Russian does this quite often with seasons and parts of the day:

• летом = in summer
• зимой = in winter
• утром = in the morning
• вечером = in the evening

So Летом хлопок подходит мне больше... means In summer, cotton suits me more...

You do also get в + prepositional with some time expressions, but for seasons, летом / зимой / весной / осенью is very standard.

In this sentence, хлопок means cotton, and the stress is on the second syllable:

хлопОк

This matters because хлОпок means something else, like a clap, a pop, or a bang.

So:

• хлопОк = cotton
• хлОпок = clap / popping sound

That is a very common learner question, because Russian usually does not mark stress in normal writing.

Here подходит means something like:

• suits
• is suitable for
• works for

So хлопок подходит мне больше means cotton suits me more or cotton is more suitable for me.

The verb is подходить. In other contexts it can also mean to approach / come closer, but here it clearly means to suit / fit / be appropriate.

For example:

• Этот цвет мне подходит. = This color suits me.
• Это время мне не подходит. = This time doesn’t work for me.

Because подходить takes the dative case for the person.

The pattern is:

что подходит кому?
what suits whom?

So:

• мне = to me
• тебе = to you
• ему / ей = to him / her

Examples:

• Мне подходит хлопок. = Cotton suits me.
• Тебе подходит этот стиль. = This style suits you.

So in the sentence, мне is there because Russian says, literally, cotton is suitable to me.

Here больше means more in the sense of to a greater degree.

So:

• хлопок подходит мне больше = cotton suits me more

It does not mean cotton is physically bigger than silk. It is comparing degree of suitability.

A natural English translation is:

• In summer, cotton suits me more than silk.
• In summer, cotton is more suitable for me than silk.

Yes, лучше would also be possible:

• Летом хлопок подходит мне лучше, чем шёлк.

That means In summer, cotton suits me better than silk.

The difference is small:

• больше = more
• лучше = better

With подходить, both can sound natural.
Лучше подходит may sound a bit more idiomatic to some speakers, while больше подходит emphasizes degree: cotton suits me more than silk does.

So the given sentence is correct and natural.

Чем means than in comparisons.

It is used after comparative words like:

• больше = more
• меньше = less
• лучше = better
• хуже = worse

So:

• больше, чем шёлк = more than silk
• лучше, чем шёлк = better than silk

In this sentence, чем introduces the thing being compared: silk.

Because чем шёлк is understood as a shortened comparison:

Летом хлопок подходит мне больше, чем шёлк [подходит мне].

In full, that would be:

• Cotton suits me more than silk suits me.

Since шёлк is really the subject of the omitted second clause, it stays in the nominative.

This is an important contrast:

• больше, чем шёлк = more than silk
• больше шёлка = more silk

The second one is not a comparison between cotton and silk; it means a larger quantity of silk.

Yes, it is important for pronunciation.

Шёлк is pronounced roughly like shyolk, with ё always stressed.

A useful rule: ё always carries the stress.

In many Russian texts, people replace ё with е, so you may also see шелк, but the word is still pronounced шёлк.

So:

• written carefully: шёлк
• often seen in everyday text: шелк
• pronunciation: still шёлк

Yes. Russian word order is flexible, and changing it changes the emphasis more than the basic meaning.

The original sentence:

Летом хлопок подходит мне больше, чем шёлк.

puts Летом first, so the sentence begins by setting the time frame: In summer...

Other possible orders include:

• Мне летом хлопок подходит больше, чем шёлк.
• Хлопок летом подходит мне больше, чем шёлк.

These all mean roughly the same thing, but the focus shifts slightly:

• first position often highlights what comes first
• later position can make something sound less emphasized

So the original version is very natural if the speaker wants to start with In summer.

Because this sentence is describing a general, ongoing preference, not one completed event.

Подходить is imperfective and works well for:

• general truths
• habits
• repeated situations
• states

Here the meaning is something like:

• In summer, cotton tends to suit me more than silk.

If you used the perfective подойти, it would usually refer to a specific result in a specific situation, not this kind of general statement.

So подходит is exactly what you want here.