Я не могу не улыбаться, когда эта певица начинает свою первую арию.

This is a very common Russian pattern:

• не могу = I cannot
• не улыбаться = not smile

Together, не могу не улыбаться literally looks like I cannot not smile, but in natural English it means:

• I can’t help smiling
• I can’t help but smile

So this is not a mistake or a double negative that cancels itself out in the English way. In Russian, this structure is standard and expresses that something is impossible to resist.

Because улыбаться is the imperfective form, and it focuses on the process or repeated action of smiling.

Compare:

• улыбаться = to smile, to be smiling, to keep smiling
• улыбнуться = to smile once, to give a smile

In Я не могу не улыбаться, the idea is not just one quick smile. It suggests an ongoing or automatic reaction: whenever this happens, the speaker ends up smiling.

So улыбаться fits better than улыбнуться.

Когда means when.

In this sentence, it introduces a time clause:

• когда эта певица начинает свою первую арию = when this singer begins her first aria

It can also have the sense of whenever in context, especially if the sentence describes a repeated situation rather than one single event.

So here it could feel like:

• when
• or more naturally in some contexts, whenever

Эта means this, so:

• певица = singer
• эта певица = this singer

The speaker is referring to a specific female singer. Russian often uses demonstratives like этот / эта / это / эти when pointing out a particular person or thing.

Also notice the agreement:

• эта is feminine singular nominative
• певица is feminine singular nominative

They match because певица is a feminine noun.

Yes. Певица specifically means female singer.

The masculine equivalent is:

• певец = male singer

So Russian often marks the person’s gender directly in the noun. In this sentence, the singer is clearly female, so певица is the correct word.

Начинает is the present-tense form of начинать.

Russian present tense is often used for:

• general truths
• repeated actions
• habitual situations

So in this sentence, the meaning is something like:

• Whenever this singer begins her first aria, I can’t help smiling

That is why present tense works well. It does not have to mean that the action is happening right this second. It can describe a regular reaction.

Also, начинает is imperfective, which suits a repeated or habitual event. If you used начнёт, that would sound more like one specific future occasion.

This is an important point. Свой is the reflexive possessive pronoun, and it is often used when the possessor is the subject of the same clause.

Here, in the clause

• эта певица начинает свою первую арию

the subject is эта певица, so свою means her own.

Why not её?

• свою арию = her own aria
• её арию = her aria, but this can sound less natural here and may sometimes suggest someone else’s aria, depending on context

Russian strongly prefers свой when the thing belongs to the subject of the clause.

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

The verb начинать takes a direct object:

• начинать что? = to begin what?

So:

• своя первая ария = nominative
• свою первую арию = accusative

All three words are feminine singular and change to match the accusative:

• своя → свою
• первая → первую
• ария → арию

That is why the whole phrase changes form.

Not necessarily. Grammatically, первую арию simply means the first aria.

What it refers to depends on context. It could mean:

• the first aria in a performance
• the first aria she sings in an opera
• the opening aria in her set

It does not automatically mean the first aria of her life or her debut aria. Context decides that.

Yes, Russian word order is more flexible than English word order.

The neutral order here is:

• Я не могу не улыбаться, когда эта певица начинает свою первую арию.

But other orders are possible for emphasis, for example:

• Когда эта певица начинает свою первую арию, я не могу не улыбаться.

This puts more focus on the time clause first, something like:

• When this singer begins her first aria, I can’t help smiling.

The basic meaning stays the same, but the emphasis and flow can change.

Yes, very common. The pattern

• не мочь не + infinitive

means:

• cannot help doing
• cannot fail to do
• cannot but do

Some examples:

• Я не могу не согласиться. = I can’t help agreeing.
• Он не мог не заметить этого. = He couldn’t fail to notice that.
• Мы не можем не думать об этом. = We can’t help thinking about it.

So once you learn this pattern, you will start seeing it often.

Yes. Because it is imperfective, улыбаться can suggest:

• smiling in general
• smiling repeatedly
• continuing to smile
• the act of smiling as a reaction

In this sentence, it does not have to mean one brief smile. It gives a broader sense: the speaker naturally ends up smiling when the singer begins.

That is one reason the imperfective works so well here.

A very literal translation would be:

• I cannot not smile when this singer begins her first aria.

That is useful for understanding the structure, especially the double negative. But in natural English, you would usually say:

• I can’t help smiling when this singer begins her first aria.
• I can’t help but smile when this singer begins her first aria.

So the literal version helps you see the grammar, but it is not the most natural English translation.