Por la noche, me quito el rímel con desmaquillante y luego me pongo el pijama.

Por la noche is the usual way to say at night / in the evening when talking about a general routine.

So:

• Por la noche = at night, in the evenings
• Por la mañana = in the morning
• Por la tarde = in the afternoon / evening

For a habitual action, por la noche sounds very natural in Spain. En la noche is less common in this kind of everyday sentence and can sound more like during the night in some contexts.

Because both verbs are being used in their pronominal forms:

• quitarse = to take off / remove from oneself
• ponerse = to put on oneself

The me shows that the subject is doing the action to themselves:

• me quito = I take off / remove
• me pongo = I put on

This is very common in Spanish with clothes, accessories, and personal care actions.

The version without the pronoun is more general. The version with the pronoun often means the action is done to oneself.

Examples:

• Quito el libro de la mesa = I remove the book from the table

• Me quito el abrigo = I take off my coat

• Pongo la taza en la mesa = I put the cup on the table
• Me pongo el pijama = I put on my pajamas

So in your sentence, me quito and me pongo are used because the speaker is removing makeup from themselves and putting clothes on themselves.

Spanish often uses the definite article (el, la, los, las) instead of a possessive (mi, tu, su) when the owner is already obvious.

Here, because the verb is reflexive (me quito), it is already clear whose mascara is meant: the one the speaker is wearing.

So Spanish prefers:

• me quito el rímel rather than
• me quito mi rímel

This is similar to how Spanish often says:

• me lavo las manos = I wash my hands
• me pongo el abrigo = I put on my coat

Yes, rímel is a common word in Spain for mascara. It comes from the brand name Rimmel, which became a common noun in Spanish.

It is usually:

• masculine: el rímel
• written with an accent: rímel

You may also hear:

• máscara de pestañas

That is a more descriptive term, while rímel is very common in everyday speech.

Because desmaquillante is being used here in a general, substance-like way, similar to with makeup remover in English.

So:

• con desmaquillante = using makeup remover, with makeup remover in general

If you wanted to talk about a specific product, you could say:

• con un desmaquillante suave = with a gentle makeup remover
• con el desmaquillante que compré ayer = with the makeup remover I bought yesterday

Without an article, it sounds general and natural.

Desmaquillante means makeup remover.

It comes from the idea of removing makeup:

• maquillar = to put makeup on
• desmaquillar = to remove makeup
• desmaquillante = makeup-removing product / makeup remover

In this sentence, it refers to the product used to take off the mascara.

In Spanish, pijama is usually a singular noun when referring to the garment or set of clothes worn for sleeping.

So:

• me pongo el pijama = I put on my pajamas

Even though English usually uses the plural pajamas, Spanish normally uses the singular pijama.

You would use the plural pijamas only when talking about several sets:

• Tengo tres pijamas = I have three pairs/sets of pajamas

For the same reason as el rímel: Spanish often uses the definite article when the owner is obvious.

Since me pongo already tells us the speaker is putting it on themselves, Spanish naturally says:

• me pongo el pijama

Using mi pijama is possible, but it is less natural unless you want to emphasize ownership, contrast, or clarity.

Luego means then, afterwards, or later.

In this sentence, it shows the order of actions:

1. me quito el rímel con desmaquillante
2. luego me pongo el pijama

So y luego is basically and then.

Because in Spanish, the present tense is very commonly used for habits and routines.

So:

• Por la noche, me quito el rímel... means something like At night / In the evenings, I remove my mascara...

This is just the normal way to describe what someone usually does.

Yes, you could say:

• Por la noche, me desmaquillo y luego me pongo el pijama.

That means At night, I take my makeup off and then put on my pajamas.

The difference is that me desmaquillo is more general. It means removing makeup overall, while:

• me quito el rímel con desmaquillante

is more specific: it tells you exactly what is being removed and how.