Зимой важно увлажнять кожу после душа.

Зимой is the instrumental singular of зима. In Russian, the names of seasons are very often used in the instrumental to mean in winter / in spring / in summer / in autumn.

So:

• зимой = in winter
• весной = in spring
• летом = in summer
• осенью = in autumn

This is a very common time expression. You can also sometimes use зимой in a broader sense like during the winter season or in winter generally.

Because this is an impersonal construction.

In Russian, when you say It is important to..., you often use:

• важно
  • infinitive

So:

• Важно увлажнять кожу. = It is important to moisturize the skin.

There is no specific subject like it in the sentence. English needs the dummy subject it, but Russian does not. The neuter short-form adverb/predicative важно is the normal form here.

Увлажнять is the imperfective form, and it is used here because the sentence expresses a general recommendation / habitual action, not one single completed act.

Compare:

• Важно увлажнять кожу после душа.
  = It’s important to moisturize the skin after showering / as a regular practice.

• Важно увлажнить кожу.
  = It’s important to moisturize the skin.
  This sounds more like a single result-oriented action: make sure the skin gets moisturized.

For advice about routines, Russian very often prefers the imperfective.

Because кожу is the accusative singular of кожа, and it is the direct object of увлажнять.

Dictionary form:

• кожа = skin

Accusative singular:

• кожу

So:

• увлажнять что? → кожу

This is just the normal case used for a direct object.

Because the preposition после always takes the genitive case.

Dictionary form:

• душ = shower

Genitive singular:

• душа

So:

• после душа = after a shower / after showering

A few more examples:

• после работы = after work
• после ужина = after dinner
• после тренировки = after training/workout

Russian often leaves out possessive words like my, your, his, etc. when the meaning is obvious from context.

So:

• увлажнять кожу literally = to moisturize the skin

But in natural English, you would usually say your skin here. Russian does not need to make that explicit unless there is a contrast or special emphasis.

If needed, you could say:

• увлажнять свою кожу = moisturize your own skin

But in this sentence, that would usually sound unnecessary.

Yes, from an English point of view, it is.

Russian often uses impersonal sentences where English uses it as a grammatical placeholder.

So:

• Зимой важно увлажнять кожу после душа.
• literally: In winter, important to moisturize skin after a shower.

But that is completely normal in Russian. The sentence is grammatically complete without any word for it.

Yes. Russian word order is more flexible than English word order, although the neutral version here is very natural:

• Зимой важно увлажнять кожу после душа.

You could also say:

• Важно зимой увлажнять кожу после душа.
• Увлажнять кожу после душа зимой важно.

These alternatives change the focus or emphasis slightly, but not the basic meaning.

The original version is a very natural way to present the information:

1. when? — зимой
2. what is important? — увлажнять кожу после душа

Usually it means after showering / after taking a shower in a general sense.

Russian often uses a noun phrase where English might use a verbal phrase:

• после душа = after a shower / after showering
• после еды = after food / after eating
• после сна = after sleep / after sleeping

Without more context, после душа here is understood as part of a routine, not one specific shower.

Yes, увлажнять means to moisturize / to hydrate / to add moisture to.

In skincare contexts, it is a very natural verb. Depending on context, Russian might also use expressions with products, for example:

• наносить увлажняющий крем = to apply moisturizing cream
• увлажнять кожу кремом = to moisturize the skin with cream

So the sentence does not name the product, but the meaning is clear: you should do something that moisturizes the skin after showering.

A helpful stress guide is:

• зимОй
• вАжно
• увлажнЯть
• кОжу
• пОсле
• душА

So the full sentence is pronounced approximately as:

• зимОй вАжно увлажнЯть кОжу пОсле душА

For an English speaker, one useful thing to notice is that Russian stress is mobile and unpredictable, so it is worth learning words together with their stress.