Перед сном я сказал бабушке «Спокойной ночи».

Because перед normally requires the instrumental case when it means before / in front of.

• сон = sleep (dictionary form, nominative)
• сном = instrumental singular

So:

• перед сном = before sleep / before going to sleep

This is a very common pattern:

• перед уроком = before class
• перед работой = before work
• перед ужином = before dinner

In Russian, time expressions like before X often use this structure.

Because the verb сказать takes the person you speak to in the dative case.

The pattern is:

• сказать кому? что?
• to say to whom? what?

So here:

• бабушка = grandmother (nominative)
• бабушке = to grandmother / to grandma (dative)

Examples:

• Я сказал брату... = I said to my brother...
• Она сказала учителю... = She said to the teacher...

So бабушке is the normal form after сказал.

This is one of the most common things learners ask.

Спокойной ночи is a fixed expression meaning good night, and both words are in the genitive case:

• спокойная ночь = a calm night (dictionary form)
• спокойной ночи = literally something like of a peaceful night

Why genitive? Historically and structurally, this kind of expression comes from an implied wish, something like:

• Желаю спокойной ночи = I wish you a peaceful night

Even when желаю is left out, the genitive phrase stays:

• Спокойной ночи!

The same thing happens in other greetings/wishes:

• Доброго утра = good morning
• Хорошего дня = have a nice day

So this is not random; it is a common Russian pattern for wishes.

Because сказать and говорить are different in aspect and usage.

• сказать = perfective; to say, to utter something as a completed act
• говорить = imperfective; to speak, to be saying, to talk, or to say repeatedly/habitually

In this sentence, the speaker said one specific thing one time, so сказал fits naturally.

Compare:

• Я сказал бабушке: ... = I said to grandma: ...
• Я говорил с бабушкой = I was talking with grandma
• Я часто говорил бабушке это = I often said this to grandma

So сказал focuses on a single completed speech act.

Yes. Literally, перед сном means before sleep.

In natural English, that usually becomes:

• before going to bed
• before sleeping
• at bedtime

Russian often uses a noun where English might prefer a more verbal expression.

So Перед сном is a very natural Russian time phrase.

Yes, Russian often can leave it out, because the verb form already shows the person and gender in context.

• я сказал = I said
• сказал by itself can often imply I said if the context is clear

So the sentence could also be:

• Перед сном сказал бабушке Спокойной ночи.

But including я is completely normal too. It may make the sentence clearer, more neutral, or slightly more explicit.

Russian pronouns are often omitted when they are obvious, but they are not wrong when included.

Yes, Russian word order is flexible.

This sentence starts with Перед сном to set the scene first:

• Before bed, I said to grandma...

That is very natural.

Other word orders are possible, for example:

• Я перед сном сказал бабушке Спокойной ночи.
• Бабушке я перед сном сказал Спокойной ночи.

These all mean roughly the same thing, but the emphasis changes:

• Перед сном... emphasizes the time
• Я... emphasizes the speaker
• Бабушке... emphasizes who was spoken to

So the given order is natural and probably the most neutral if the speaker wants to begin with the time phrase.

Those are standard Russian quotation marks, often called angle quotes or guillemets:

• « ... »

Russian typically uses these instead of English-style " ... " in printed text.

Here they show the exact words that were said:

• Спокойной ночи

In informal typing, especially online, Russians may also use regular straight quotation marks, but « » are the standard literary/published form.

Yes. It represents the exact words the speaker said to grandma.

So the structure is:

• narrative part: Перед сном я сказал бабушке
• direct speech: Спокойной ночи

In English, that is like:

• Before bed, I said to grandma, Good night.

Russian often handles direct speech a bit differently from English in punctuation and formatting, but the basic idea is the same: these are the actual words spoken.

In standard Russian punctuation, many writers would indeed write:

• Перед сном я сказал бабушке: «Спокойной ночи».

That colon introduces the direct speech.

So if you are learning standard written Russian, it is a good idea to expect the version with a colon.

The version without the colon may appear in simplified examples, informal contexts, or materials that are focusing more on grammar than punctuation. But from a strict punctuation point of view, the colon is the safer standard choice here.

Because different Russian verbs require different cases and prepositions.

With сказать:

• сказать бабушке = say to grandma
• person spoken to = dative

But with говорить с бабушкой:

• говорить с бабушкой = talk with grandma
• с
  • instrumental

So compare:

• Я сказал бабушке Спокойной ночи.
• Я говорил с бабушкой перед сном.

This is a very important point in Russian: verbs often control different case patterns, even when the English translation seems similar.

Yes. Бабушка can mean either grandmother or grandma, depending on context and tone.

In many everyday contexts, English speakers would naturally translate it as grandma, because that sounds warmer and more natural in family situations.

Russian also has more affectionate or informal variants, such as:

• бабуля
• бабушка in a warm tone already often feels affectionate

So in this sentence, grandma is usually the most natural English equivalent.

No. It is specifically a good night / sleep well kind of expression, usually said when someone is going to bed or when parting late at night.

So it is not the same as a general evening greeting.

Compare:

• Добрый вечер = good evening
• Спокойной ночи = good night

So if you see someone at 9 p.m., you might say Добрый вечер.
If they are going to bed, you say Спокойной ночи.