Когда я говорю, мой друг кивает и улыбается.

In Russian, a subordinate clause is normally separated by a comma.

Here, Когда я говорю is a time clause meaning when I speak / when I’m speaking, and the main clause is мой друг кивает и улыбается.

So the comma is required:

Когда я говорю, мой друг кивает и улыбается.

This is similar to English, where a comma is often used when a when-clause comes first.

Когда means when.

In this sentence, it introduces a time relationship:

• Когда я говорю = when I speak / when I am speaking
• мой друг кивает и улыбается = my friend nods and smiles

Depending on context, Russian present tense here can sound like:

• when I speak
• when I’m speaking
• whenever I speak

So когда does not always point to just one single moment; it can also describe a usual repeated situation.

Говорю is the 1st person singular present tense form of говорить (to speak / to talk / to say in some contexts).

The subject is я (I), so the verb must match it:

• я говорю = I speak / I am speaking
• ты говоришь = you speak
• он/она говорит = he/she speaks

So я говорю is simply the correct form for I.

Because мой друг is the subject of the main clause, so it is in the nominative case.

• мой = my (masculine nominative singular)
• друг = friend (masculine nominative singular)

Together:

• мой друг = my friend

You would use a different case only if the phrase had a different job in the sentence, for example as an object.

Because in Russian, just like in English, one subject can control more than one verb.

So:

• мой друг кивает и улыбается
  means
• my friend nods and smiles

Russian does not need to repeat the subject:

• мой друг кивает и улыбается
  not
• мой друг кивает и мой друг улыбается

The second version is grammatical, but repeating the subject would usually sound unnecessary unless you wanted emphasis.

Кивает is the 3rd person singular present tense form of кивать (to nod).

The subject is мой друг (my friend), which is grammatically he-type singular, so the verb takes the 3rd person singular form:

• я киваю = I nod
• ты киваешь = you nod
• он/она кивает = he/she nods

So мой друг кивает = my friend nods / is nodding.

Because the verb is улыбаться, which is a reflexive verb.

In Russian, улыбаться means to smile. Even though English does not use a reflexive form here, Russian does.

So:

• улыбаться = to smile
• улыбается = he/she smiles

The -ся is part of the verb itself, not a separate word. You should learn улыбаться as the normal dictionary form.

Historically, yes, the -ся element comes from a reflexive form, but in modern Russian you usually just treat улыбаться as the normal verb for to smile.

So for a learner, the most useful approach is:

• memorize улыбаться = to smile
• memorize улыбается = he/she smiles

You do not need to translate the reflexive part literally in English.

Yes. Russian present tense often covers both:

• an action happening now
• a habitual or repeated action

So this sentence can mean either:

• When I’m speaking, my friend is nodding and smiling or
• Whenever I speak, my friend nods and smiles

Because the sentence uses говорю, кивает, улыбается in the present tense, it feels natural for a general or ongoing situation.

Because the sentence describes an ongoing or repeated situation, not a single completed event.

Говорить is imperfective, which is the normal choice for:

• ongoing action
• repeated action
• general process

Here, Когда я говорю means when I am speaking / whenever I speak, so imperfective is exactly what Russian wants.

A perfective verb would suggest a completed event and would not fit this sentence as naturally.

Yes, Russian word order is flexible.

The neutral order here is:

Когда я говорю, мой друг кивает и улыбается.

But you could also say:

Мой друг кивает и улыбается, когда я говорю.

This has the same basic meaning: My friend nods and smiles when I speak.

The first version puts the time setting first. The second puts the main action first. Both are natural.

It can be either, depending on context.

Russian present tense does not force the same distinction that English often makes between:

• I speak
• I am speaking

So Когда я говорю may mean:

• when I speak
• when I am speaking
• whenever I speak

You choose the best English translation from context, not from the verb form alone.

The main stress points are:

• когда́
• говорю́
• мой друг
• ки́вает
• улыба́ется

A rough pronunciation guide:

• Когда я говорю ≈ kag-DA ya ga-va-RYU
• мой друг ≈ moy drook
• кивает ≈ KEE-va-yet
• улыбается ≈ oo-ly-BA-ye-tsa

A few useful notes:

• unstressed о often sounds closer to a
• я after a consonant can sound like ya
• -ется / -ается is often pronounced a bit more smoothly in fast speech than spelling may suggest

Not always, but here they are natural and clear.

• Я can sometimes be omitted in Russian because the verb form говорю already shows I.
• мой is often kept when you specifically mean my friend, though in some contexts Russian may omit possessives more often than English does.

So you might hear:

• Когда говорю, мой друг кивает и улыбается.

This is possible, because говорю already tells us the subject is I. But the full version with я is completely normal and very clear for learners.