Перед сном я сниму очки и выключу свет.

Сном is in the instrumental case.

After the preposition перед when it means before / in front of, Russian normally uses the instrumental:

• перед домом — in front of the house
• перед ужином — before dinner
• перед сном — before sleep / before going to bed

The base noun is сон (sleep), and its instrumental singular form is сном.

So перед сном literally means something like before sleep.

Because Russian prepositions usually require a specific case, and перед does not take the nominative here.

• dictionary form: сон
• after перед: сном

So перед сон would be ungrammatical.

Сниму is the 1st person singular future form of the perfective verb снять.

• снять — infinitive, to take off / remove
• сниму — I will take off

Compare:

• я снимаю очки — I am taking off / I take off glasses
• я сниму очки — I will take off the glasses

Here the sentence talks about a future completed action done before bed, so сниму is the natural choice.

Because the sentence describes two actions that will happen later.

• сниму — I will take off
• выключу — I will switch off

Both are also perfective verbs, which is important: the speaker means each action as a single completed event.

That fits the idea of a bedtime routine:

1. take off glasses
2. turn off the light

Russian often uses the perfective aspect when talking about actions as complete results.

In this sentence, the speaker is not focusing on the process, but on the fact that the actions will be done:

• сниму очки — I will take the glasses off
• выключу свет — I will turn the light off

If you used imperfective forms, it would sound more like repeated/habitual action or focus on process, depending on context.

So perfective is natural here because these are simple one-time completed actions in the future.

They are in the accusative case, because they are the direct objects of the verbs:

• сниму что? — очки
• выключу что? — свет

For inanimate masculine and plural nouns, the accusative often looks exactly like the nominative:

• очки — nominative plural / accusative plural
• свет — nominative singular / accusative singular

So the forms do not change here, even though the case is accusative.

In normal Russian, очки (glasses) is a plural-only noun in this meaning, like English glasses or scissors.

So you say:

• эти очки — these glasses
• мои очки — my glasses
• снять очки — take off one’s glasses

The singular очко exists, but it does not mean one lens of your glasses in normal everyday speech. It has other meanings, so learners should treat очки as the standard word for a pair of glasses.

No. Снять is a very common verb with several meanings depending on context. Some common ones are:

• снять пальто — take off a coat
• снять очки — take off glasses
• снять квартиру — rent an apartment
• снять деньги — withdraw money
• снять фильм — shoot/make a film

So in this sentence, снять specifically means to remove / take off.

Russian has no articles like a / an / the.

So:

• очки can mean glasses, the glasses, or a pair of glasses
• свет can mean light or the light

Context tells you which interpretation is natural. In this sentence, English usually uses the glasses and the light, but Russian does not need separate words for that.

Yes. Russian often drops subject pronouns when the verb ending already shows who the subject is.

So all of these are possible:

• Перед сном я сниму очки и выключу свет.
• Перед сном сниму очки и выключу свет.

Since сниму and выключу clearly mean I will..., я is not strictly necessary.

Including я can make the subject a bit more explicit, clearer, or slightly more natural depending on context.

Because Russian word order is flexible, and speakers often put a time expression near the beginning to set the scene:

• Перед сном я сниму очки и выключу свет.

This means roughly: As for before bed, I’ll take off my glasses and turn off the light.

But other orders are also possible, for example:

• Я перед сном сниму очки и выключу свет.

The beginning position is very natural because it establishes when the actions happen.

Because both verbs have the same subject: I.

Russian, like English, can use one subject with multiple coordinated verbs:

• я сниму очки и выключу свет
  = I will take off my glasses and turn off the light

There is no need to repeat я before the second verb unless you want special emphasis.

Yes, it is a very common and natural phrase.

• выключить свет — to turn off the light
• включить свет — to turn on the light

So выключу свет means I will turn off the light.

Russian often uses light in the singular this way, just as English does.

Перед сном is a short, natural, idiomatic way to say before sleep / before bed.

A longer phrase such as перед тем как лечь спать means before going to bed and is also possible, but it is more explicit and heavier.

Compare:

• Перед сном я почитаю. — Before bed, I’ll read.
• Перед тем как лечь спать, я почитаю. — Before going to bed, I’ll read.

In your sentence, перед сном is simpler and very natural.

The main stress is:

• пе́ред сном
• я сниму́ очки́
• и вы́ключу свет

A rough pronunciation guide:

• перед — PYE-red
• сном — snom
• сниму́ — snee-MOO
• очки́ — a-chee
• вы́ключу — VY-klyu-chu
• свет — svyet

A useful thing to notice is that сниму́ and очки́ are stressed at the end, while вы́ключу is stressed near the beginning.