Она открыла косметичку, достала салфетку и начала смывать макияж перед сном.

Because the subject is она (she), and these are all past tense feminine singular forms.

In Russian past tense, the verb agrees with gender and number:

• он открыл = he opened
• она открыла = she opened
• оно открыло = it opened
• они открыли = they opened

So here:

• она открыла
• она достала
• она начала

The subject она is only stated once, but it applies to all three verbs.

They are in the accusative case because they are direct objects: the things she opened and took out.

Both косметичка and салфетка are feminine nouns ending in -а, and in the singular accusative they usually change like this:

• -а → -у
• -я → -ю

So:

• косметичка → косметичку
• салфетка → салфетку

In this sentence:

• открыла косметичку = opened the makeup bag
• достала салфетку = took out a wipe/tissue

Косметичка means a makeup bag, cosmetic bag, or toiletry pouch, depending on context.

It refers to the small bag or case where someone keeps cosmetics. In this sentence, it is most naturally makeup bag.

Even though the ending may look diminutive to a learner, косметичка is the standard everyday word, not necessarily an especially cute or tiny version.

Because достать / доставать means to take out, to get out, or to pull out, often from some container or place.

That fits this sentence very well:

• she opened the makeup bag
• then took out a wipe from it

If you said взяла салфетку, that would just mean took a wipe. It does not emphasize that she took it out of the bag.

So достала is more precise here.

Начала смывать means began to wash off.

Russian often uses:

• начать / начинать + infinitive

So:

• начала смывать = began to wash off
• literally: started to wash off

This construction is very common when the sentence focuses on the start of an action rather than the whole action being completed.

This is a very common aspect question.

• смывать = imperfective
• смыть = perfective

After начать / начинать, Russian very often uses the imperfective infinitive, because the meaning is about starting a process.

So:

• начала смывать макияж = she began washing off her makeup

This sounds natural because removing makeup is seen as an activity/process in progress.

Using начала смыть is much less natural in standard usage here.

A useful rule of thumb: after begin/start, Russian usually prefers the imperfective infinitive.

Yes. Смывать макияж is a very normal and idiomatic way to say wash off/remove makeup.

The verb смывать literally means to wash off.

So:

• смывать макияж = to wash off makeup
• смыть макияж = to wash off makeup completely / successfully

Other expressions exist, but this one is very natural when someone is physically washing their makeup off before bed.

Because макияж here is also a direct object, and for this noun the accusative singular looks the same as the nominative singular.

• макияж = nominative
• макияж = accusative

That is normal for many inanimate masculine nouns in Russian.

So:

• смывать макияж = wash off makeup

No ending change is needed.

Сном is the instrumental singular of сон (sleep).

The preposition перед usually takes the instrumental case when it means before or in front of.

So:

• сон = sleep
• сном = instrumental form
• перед сном = before sleep / before going to bed

This is a very common fixed expression in Russian.

Compare:

• перед ужином = before dinner
• перед работой = before work
• перед сном = before bed

Yes. Literally it is before sleep, but in natural English translation it is often before bed or before going to sleep.

Russian often uses сон (sleep) where English prefers bed in this kind of everyday expression.

So перед сном is completely natural and very common.

Because once the subject is clear, Russian does not need to repeat it.

In this sentence, all three actions belong to the same person:

• Она открыла косметичку
• (она) достала салфетку
• (она) начала смывать макияж

Repeating она each time would sound unnecessary unless you wanted special emphasis.

This is similar to English:

• She opened her makeup bag, took out a wipe, and began removing her makeup before bed.

English also normally mentions she only once here.

Yes. Russian word order is fairly flexible, though this version is very natural.

The sentence as written presents the actions in a smooth sequence:

1. открыла косметичку
2. достала салфетку
3. начала смывать макияж
4. перед сном

You can move parts around for emphasis, for example:

• Перед сном она открыла косметичку, достала салфетку и начала смывать макияж.

This puts before bed first, making the time frame more prominent.

So the original word order is not the only possible one, but it is a very standard neutral order.

Because Russian uses commas to separate the sequence of actions in this kind of compound predicate structure.

Here we have three past-tense verbs connected in a series:

• открыла
• достала
• начала смывать

The comma separates the first two actions, and и joins the last one:

• Она открыла косметичку, достала салфетку и начала смывать макияж перед сном.

This is similar to English punctuation in a list of actions:

• She opened the bag, took out a wipe, and began removing her makeup.

Yes, aspect matters a lot here.

• открыла ← открыть: perfective
• достала ← достать: perfective
• начала ← начать: perfective
• смывать: imperfective infinitive

Why this combination?

• открыла = she completed the action of opening
• достала = she completed the action of taking out
• начала = she completed the action of beginning
• смывать = the washing-off itself is presented as an ongoing process

So the sentence moves naturally through completed steps and then into the process that started.

That is a very typical and elegant Russian aspect pattern.