Мне нравятся лёгкие духи, а сестра сегодня заплела косу и вообще ими не пользовалась.

Russian often uses нравиться to express that something is pleasing to someone.

• Мне нравятся лёгкие духи literally means Light perfumes are pleasing to me.
• A more natural English translation is I like light perfume.

Compare:

• Я люблю... = I love...
• Мне нравится / нравятся... = I like...

So нравиться is usually the better match for ordinary like.

Also, with нравиться, the person who likes something goes in the dative case:

• мне = to me
• тебе = to you
• ему/ей = to him/her

That is why it is мне нравятся, not я нравлюсь or something similar.

Because the grammatical subject is духи, and духи is plural.

With нравиться, the verb agrees with the thing being liked, not with the person in the dative.

• Мне нравится книга. = I like the book.
• Мне нравятся книги. = I like books.
• Мне нравятся духи. = I like perfume.

Since духи is grammatically plural, the verb must also be plural: нравятся.

In Russian, духи meaning perfume is a plural-only noun. This is one of those words that are grammatically plural even when English uses a singular or mass noun.

So:

• духи = perfume
• эти духи = this perfume / these perfumes, depending on context

Because it is plural grammatically, other words around it are also plural:

• лёгкие духи
• мне нравятся духи
• ими не пользовалась

This is similar to how some English nouns behave unusually, though not in exactly the same way.

Лёгкие is the plural form of лёгкий, meaning light.

With perfume, light means something like:

• not too strong
• delicate
• subtle

Because духи is plural, the adjective must also be plural:

• masculine singular: лёгкий
• feminine singular: лёгкая
• neuter singular: лёгкое
• plural: лёгкие

So:

• лёгкие духи = light perfume

Заплела косу means braided her hair into a braid or more simply braided her hair.

Here:

• заплела = past tense, feminine, from заплести
• косу = a braid / plait, accusative singular of коса

In Russian, заплести косу is a normal expression meaning to make the hair into a braid.

So the idea is that the sister styled her hair in a braid today.

Because the sentence refers to one braid.

Russian uses:

• заплести косу = to braid one’s hair into a single braid
• заплести косы = to make braids / two braids / multiple braids

So косу tells us she made a single braid.

In the past tense, Russian verbs agree in gender and number with the subject.

The subject here is сестра, which is feminine singular, so the verb is also feminine singular:

• masculine: заплёл
• feminine: заплела
• neuter: заплело
• plural: заплели

So:

• сестра заплела косу = the sister braided her hair / made a braid

The same thing happens later with пользовалась, which is also feminine because it still refers to сестра.

Заплела is perfective, which presents the action as completed.

That fits the context well:

• today she did braid her hair
• the action is seen as a finished event

If you said заплетала, that would be imperfective, which could suggest:

• a repeated action
• a process
• background information
• something habitual

So here заплела is natural because it refers to one completed action today.

Because the verb пользоваться requires the instrumental case, not the accusative.

So:

• nominative: они
• accusative: их
• instrumental: ими

Since духи is plural, the correct instrumental pronoun is ими.

So:

• пользоваться духами = to use perfume
• ими пользовалась = used them / used it

Even though English says use them/it, Russian uses the instrumental after пользоваться.

Пользовалась is:

• past tense
• feminine singular
• reflexive form
• from пользоваться = to use

It matches сестра, which is feminine singular.

Compare:

• я пользовался = I used (male speaker)
• я пользовалась = I used (female speaker)
• она пользовалась = she used
• они пользовались = they used

The -сь / -ся ending is part of the verb itself here.

That is simply the case pattern this verb requires.

In Russian, different verbs govern different cases. For пользоваться, you use the instrumental:

• пользоваться телефоном = to use a phone
• пользоваться словарём = to use a dictionary
• пользоваться духами = to use perfume

With pronouns:

• пользоваться им = to use it
• пользоваться ими = to use them / it for plural nouns like духи

This is something learners usually just have to memorize together with the verb.

Here вообще means something like:

• at all
• in general
• actually, not at all in this case

In this sentence, it strengthens the negation:

• вообще ими не пользовалась = didn’t use it at all

So the idea is not just that she did not use the perfume once, but that she did not use it whatsoever.

Because in Russian, subject pronouns are often omitted when they are clear from context.

Here the subject is already established as сестра, so there is no need to repeat она.

Russian often sounds more natural this way:

• Сестра сегодня заплела косу и вообще ими не пользовалась.

You could add она, but it is usually unnecessary unless you want emphasis or contrast.

А often marks a contrast or a shift to another topic.

Here it connects two ideas:

• Мне нравятся лёгкие духи
• а сестра... ими не пользовалась

So it means something like:

• whereas
• but
• and as for my sister...

It is not always as strong as English but. Often it just signals contrast between two situations or people.

Yes, Russian word order is flexible, but the original order is very natural.

• Мне нравятся лёгкие духи puts the experiencer first, then the verb, then the thing liked.
• а сестра сегодня заплела косу и вообще ими не пользовалась flows from subject to time word to action, then to the second action.

You could rearrange some parts for emphasis, for example:

• Сегодня сестра заплела косу и вообще ими не пользовалась.
• Лёгкие духи мне нравятся...

But the original sentence sounds normal and balanced, especially in conversation or narrative.