Она выбрала лёгкие духи, потому что не любит слишком сильный запах.

Выбрала is the past tense of выбрать, which means to choose/select.

The ending -ла tells you that the subject is feminine singular, which matches она. Compare:

• он выбрал = he chose
• она выбрала = she chose
• они выбрали = they chose

So она выбрала means she chose.

Russian uses aspect to show how an action is viewed.

• выбрать = perfective, a completed choice
• выбирать = imperfective, the process/habit of choosing

In this sentence, she made one completed choice, so выбрала is natural.

• Она выбрала лёгкие духи = she chose light perfume
• Она выбирала лёгкие духи would suggest she was choosing, or used to choose, or the action is being viewed as ongoing/repeated

Because духи is a plural-only noun in Russian when it means perfume. This is called a pluralia tantum noun.

So even though English uses singular perfume, Russian normally says духи in the plural.

That is also why the adjective is plural:

• лёгкие духи = light perfume

Be careful: the singular дух does not mean one perfume. It usually means things like spirit, ghost, or breath/air in some contexts.

Adjectives must agree with the noun in gender, number, and case.

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

• лёгкие духи

If the noun were masculine singular, then you could have лёгкий. But here that would be ungrammatical.

It is in the accusative case, because it is the direct object of выбрала.

However, with inanimate plural nouns, the accusative form is the same as the nominative form. So:

• nominative: лёгкие духи
• accusative: лёгкие духи

That is why it looks unchanged.

Because любить takes the accusative case.

Here запах is:

• masculine
• singular
• inanimate

For masculine inanimate singular nouns, the accusative looks the same as the nominative. So:

• nominative: сильный запах
• accusative: сильный запах

That is why the sentence has не любит слишком сильный запах.

If it were an animate masculine noun, the accusative would look different.

Because this part expresses a general preference, not a one-time past action.

• Она выбрала... = one completed past action
• не любит... = a general fact about her tastes

So the meaning is essentially:

• She chose light perfume because she doesn't like overly strong smells.

Russian often does this, just like English.

Here лёгкие means light in the sense of not heavy, not intense, subtle, delicate.

With perfume, лёгкие духи means something like:

• light perfume
• subtle perfume
• not overpowering perfume

So this is about the strength of the scent, not physical weight.

Слишком means too or overly.

It modifies the adjective сильный, not the noun запах directly:

• слишком сильный запах = too strong a smell

Compare:

• очень сильный запах = a very strong smell
• слишком сильный запах = a too-strong smell / an overly strong smell

So слишком suggests excess, not just intensity.

Because потому что introduces a subordinate clause meaning because.

Russian normally places a comma before it:

• Она выбрала лёгкие духи, потому что не любит слишком сильный запах.

This is standard punctuation.

Yes, Russian could use the plural in some contexts, but the singular works well here.

The singular запах can express the idea of strong scent/smell as a general thing. It sounds natural when talking about the quality of perfume.

• не любит слишком сильный запах = she does not like an overly strong smell

If you used the plural, запахи, that would sound more like strong smells/scents in general.

So the singular here is not strange; it is a natural way to talk about scent as a quality.

Yes. Russian word order is more flexible than English, although the original version is the most neutral.

Original:

• Она выбрала лёгкие духи, потому что не любит слишком сильный запах.

You could also rearrange parts for emphasis, for example:

• Потому что она не любит слишком сильный запах, она выбрала лёгкие духи.

That is grammatical, but it sounds more marked or emphatic. For a learner, the original order is the safest and most natural choice.