Uso crema hidratante por la noche porque mi piel se seca en invierno.

In Spanish, subject pronouns are often omitted because the verb ending already shows who is doing the action.

• uso = I use
• The -o ending tells you the subject is yo

So:

• Uso crema hidratante... = I use moisturiser...
• Yo uso crema hidratante... is also possible, but yo is usually only added for emphasis, contrast, or clarity.

For example:

• Yo uso crema hidratante, pero mi hermano no.
  I use moisturiser, but my brother doesn’t.

Both are possible, but they mean slightly different things.

• Uso crema hidratante = I use moisturiser / I use moisturising cream in a general sense.
• Uso una crema hidratante = I use a moisturising cream, often meaning one particular product or one item among others.

Spanish often leaves out the article when talking about something in a general, uncountable, or routine way.

Compare:

• Bebo café. = I drink coffee.
• Compro pan. = I buy bread.
• Uso crema hidratante. = I use moisturiser.

If you said una crema hidratante, it would sound a bit more like you are referring to a specific type or unit of cream.

Crema hidratante means moisturiser or moisturising cream.

Spanish usually places descriptive adjectives after the noun, unlike English, where they often come before it.

• crema hidratante = moisturising cream
• literally: cream moisturising

This is very normal in Spanish:

• vino tinto = red wine
• casa grande = big house
• piel seca = dry skin

So hidratante comes after crema because that is the standard word order in Spanish.

In Spain, por la noche is the most natural way to say at night / in the evening / at nighttime, especially when talking about habits.

• Uso crema hidratante por la noche. = I use moisturiser at night.

En la noche exists, but it is less common in this kind of sentence in Spain and can sound more like during the night in some contexts.

Useful time expressions:

• por la mañana = in the morning
• por la tarde = in the afternoon/evening
• por la noche = at night / in the evening

If you are learning Spanish from Spain, por la noche is the safest choice here.

Because porque here means because and introduces the reason.

There are several similar-looking forms in Spanish:

• porque = because
• por qué = why
• el porqué = the reason
• por que = less common combination in special structures

In your sentence:

• Uso crema hidratante por la noche porque mi piel se seca en invierno.
• ...because my skin gets dry in winter.

So porque is correct because it gives the cause or explanation.

Spanish uses the present tense for habitual actions and general truths, just like English often does.

So:

• Uso crema hidratante por la noche = I use moisturiser at night
  meaning this is a routine or usual habit
• mi piel se seca en invierno = my skin gets dry in winter
  meaning this usually happens in winter

This is not necessarily happening right now. It describes what generally happens.

Compare:

• Leo por la noche. = I read at night.
• En verano hace calor. = In summer it’s hot.
• Mi piel se seca en invierno. = My skin gets dry in winter.

That is a very good question. Spanish often uses the definite article with body parts, especially when the owner is already clear from the verb or context:

• Me duele la cabeza. = My head hurts.
• Me lavo las manos. = I wash my hands.

But in this sentence, mi piel is completely natural because the speaker is simply referring to their skin as a possessed thing, not in one of those common reflexive/body-part patterns.

So:

• mi piel se seca = my skin gets dry

Using la piel here could be possible in some contexts, but mi piel sounds very normal and direct, especially when talking about skincare or personal condition.

Secarse means to become dry / to dry out.

So:

• mi piel se seca = my skin gets dry / my skin dries out

The se is part of the verb secarse, which often expresses a change of state happening to the subject.

Compare:

• secar = to dry something
• secarse = to dry up / become dry

Examples:

• El sol seca la ropa. = The sun dries the clothes.
  Here seca is transitive: something dries something else.
• La ropa se seca rápido. = The clothes dry quickly.
  Here se seca means the clothes become dry.

So in your sentence, mi piel se seca means the skin itself becomes dry.

Yes, but the meaning changes slightly.

• Mi piel se seca en invierno = My skin gets dry in winter / dries out in winter.
  This focuses on the process or tendency.
• Mi piel está seca en invierno = My skin is dry in winter.
  This focuses on the condition or result.

Both are natural, but se seca suggests that winter causes the skin to dry out, while está seca simply describes the state.

So the original sentence is especially good if you want to express what happens to your skin in winter.

When talking about seasons in a general sense, Spanish often uses en + season without the article.

• en invierno = in winter
• en verano = in summer
• en otoño = in autumn
• en primavera = in spring

So:

• mi piel se seca en invierno = my skin gets dry in winter

You may also hear en el invierno, but that is more likely in specific contexts, such as referring to a particular winter or giving it more emphasis. For a general statement, en invierno is the normal choice.

Yes. Both are correct, but there is a slight nuance.

• por la noche = at night / in the evening
• por las noches = at nights / at night regularly / night after night

In many contexts they are very close, especially when talking about habits.

Compare:

• Uso crema hidratante por la noche. = I use moisturiser at night.
• Uso crema hidratante por las noches. = I use moisturiser at night / at nights, regularly.

The plural version can make the habitual idea a bit more explicit.

Piel is feminine:

• la piel
• mi piel
• piel seca

That is why the adjective agrees in the feminine form when needed:

• La piel está seca. = The skin is dry.

Even though piel ends in -l and not -a, it is still feminine. Gender in Spanish is not always predictable just from the ending, so it is best to learn nouns together with their article:

• la piel
• la crema
• el invierno

A natural Spain Spanish pronunciation would be roughly:

OO-so KRE-ma ee-dra-TAN-te por la NO-che POR-ke mi pyel se SE-ka en im-BYER-no

A few useful pronunciation notes:

• uso: the u sounds like oo
• hidratante: the h is silent
• ll is not in this sentence, but piel has ie, pronounced like one syllable glide: pyel
• porque has the stress on por
• invierno has the stress on bier

The main stressed syllables are:

• U-so
• hi-dra-TAN-te
• NO-che
• POR-que
• SE-ca
• in-BIER-no

Yes. Depending on what exactly you mean, you might hear:

• crema hidratante = moisturising cream / moisturiser
• hidratante = moisturiser (shorter, very common in context)
• loción hidratante = moisturising lotion

For example:

• Uso hidratante por la noche.
• Uso una crema hidratante por la noche.

But crema hidratante is a very standard and clear phrase, so it is an excellent choice for learners.

The sentence is:

Uso crema hidratante por la noche porque mi piel se seca en invierno.

It breaks down like this:

• Uso = verb
• crema hidratante = direct object
• por la noche = time expression
• porque = conjunction meaning because
• mi piel = subject of the second clause
• se seca = verb
• en invierno = time expression

So the overall structure is:

[main clause] + porque + [reason clause]

That pattern is very common in Spanish:

• Estudio por la tarde porque trabajo por la mañana.
• Llevo abrigo porque hace frío.
• Uso crema hidratante por la noche porque mi piel se seca en invierno.