Перед выходом она быстро сделала маникюр и положила всё в косметичку.

Because перед in the sense of before requires the instrumental case.

• выход = exit / departure / going out
• Instrumental singular: выходом

So:

• перед выходом = before going out / before leaving

This is a very common pattern:

• перед работой = before work
• перед ужином = before dinner
• перед встречей = before the meeting

In this sentence, it means before leaving / before going out.

Russian перед can mean two different things depending on context:

1. before (time)

   • перед выходом = before going out

2. in front of (place)

   • перед домом = in front of the house
   • перед дверью = in front of the door

Here, выходом is understood as the act of going out / departure, so the phrase is temporal, not spatial.

Yes. Сделать маникюр is a standard Russian expression meaning to do one’s nails / to get a manicure / to give oneself a manicure, depending on context.

Literally, it is did a manicure, but in natural English we usually translate it more idiomatically.

A few useful points:

• маникюр is a noun, not a verb
• Russian often uses делать / сделать + noun in places where English prefers a verb phrase

Examples:

• делать уборку = to do the cleaning
• сделать макияж = to do one’s makeup
• сделать маникюр = to do one’s nails / do a manicure

They are perfective because the sentence describes completed actions in sequence.

• сделала = she completed doing the manicure
• положила = she put something away / placed it, completing the action

This fits a typical narrative use of the perfective in Russian: one finished action followed by another.

Compare:

• делала маникюр = she was doing her manicure / used to do her manicure

• сделала маникюр = she did her manicure, finished it

• клала is not the normal past form you would use here
• положила is the standard perfective verb meaning put/placed

So the sentence presents a short chain of finished events:

1. she did her manicure
2. she put everything into the makeup bag

Because в can take either the accusative or the prepositional case, depending on meaning.

Here the idea is movement into something, so Russian uses the accusative:

• в косметичку = into the makeup bag

Compare:

• в косметичке = in the makeup bag (location)
• положила всё в косметичку = she put everything into the makeup bag
• всё было в косметичке = everything was in the makeup bag

This is a very important Russian pattern:

• куда? (where to?) → accusative
• где? (where?) → prepositional

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

It comes from косметика meaning cosmetics, plus the suffix -ичк-, which often forms a small, practical object.

So in this sentence, положила всё в косметичку means she put all the relevant items into her cosmetics bag.

Всё means everything here.

It is the neuter form because Russian uses neuter singular for general, non-counted things taken as a whole:

• всё = everything
• все = all / everyone (plural)

Compare:

• Она положила всё в косметичку. = She put everything into the makeup bag.
• Она положила все вещи в косметичку. = She put all the things into the makeup bag.

Also note pronunciation:

• всё contains ё, so it is pronounced roughly like vsyo

Yes, it often could be omitted if the subject is already clear from context.

Russian frequently drops subject pronouns when the verb form already shows who is doing the action:

• сделала already tells you the subject is feminine singular in the past
• положила also shows feminine singular

So in context, Russian speakers might simply say:

• Перед выходом быстро сделала маникюр и положила всё в косметичку.

However, она is perfectly normal if the speaker wants to:

• make the subject explicit
• improve clarity
• contrast her with someone else

Быстро is an adverb meaning quickly, and its position is fairly natural here: it modifies сделала.

• она быстро сделала маникюр = she quickly did her manicure

Russian word order is more flexible than English, so you may see other possibilities too:

• Она быстро сделала маникюр.
• Она сделала маникюр быстро.

But the version in the sentence sounds very natural because the adverb comes before the verb it most directly modifies.

Also, the placement helps the sentence flow as a sequence:

• Перед выходом = before leaving
• она быстро сделала маникюр = she quickly did her manicure
• и положила всё в косметичку = and put everything into the makeup bag

Russian often leaves possession unstated when it is obvious from context.

In English, we often say:

• did her manicure
• put everything in her makeup bag

In Russian, if it is clear that these things belong to the subject, speakers often just use the noun without a possessive pronoun:

• сделала маникюр
• положила всё в косметичку

If needed, Russian can add possession explicitly:

• сделала свой маникюр
• положила всё в свою косметичку

But in many everyday sentences, that would sound unnecessary or overly explicit unless there is contrast or emphasis.