Цикл стирки начнётся завтра.

Because стирки is in the genitive case.

The base noun is стирка = washing / laundry. In the phrase цикл стирки, Russian uses a structure like cycle of washing. English often uses noun + noun (wash cycle), but Russian commonly expresses this relationship with the genitive:

• цикл = cycle
• стирки = of washing

So цикл стирки literally means the cycle of washing, which in natural English is the wash cycle.

Because начнётся is a future-tense form of the verb начаться.

Russian has two aspects:

• imperfective: focuses on process or repetition
• perfective: focuses on a completed event or single occurrence

Here, начаться is perfective, meaning to begin / to start as a single event. Perfective verbs form the simple future:

• начаться → начнётся = will begin / will start

So Цикл стирки начнётся завтра means The wash cycle will start tomorrow.

The dictionary form is начаться.

This is a reflexive verb meaning to begin or to start.
Its future forms are:

• я начнусь
• ты начнёшься
• он / она / оно начнётся
• мы начнёмся
• вы начнётесь
• они начнутся

In this sentence, цикл is a singular masculine noun, so the verb is in 3rd person singular: начнётся.

Because the verb is начаться, not начать.

The ending -ся often marks a reflexive or intransitive verb. In this case, the difference is:

• начать = to start something
• начаться = to begin / to start (by itself)

Compare:

• Я начну стирку завтра. = I will start the washing tomorrow.
• Стирка начнётся завтра. = The washing will begin tomorrow.

So in your sentence, the wash cycle is the thing that begins, which is why начнётся is used.

Yes, in many real texts you may see начнется, because Russian often omits the dots over ё in writing.

But the correct pronunciation is with ё:

• начнётся → pronounced roughly nach-NYOT-sya

Using ё is especially helpful for learners because it shows both the correct sound and the stress.

So:

• начнётся = fully marked spelling
• начнется = common unmarked spelling in everyday text

Both refer to the same word.

The main stresses are:

• цикл → ЦИкл
• стирки → СТИРки
• начнётся → начнЁтся
• завтра → ЗАвтра

A helpful pronunciation guide:

• Цикл стирки начнётся завтра
• TSIKL STIR-kee nach-NYOT-sya ZAF-tra

The most important one to notice is начнётся, because the ё always carries the stress.

Because Russian has no articles like a or the.

So цикл стирки can mean:

• a wash cycle
• the wash cycle

The exact meaning depends on context. In many situations, English translation will naturally use the:

• The wash cycle will start tomorrow.

Russian does not need a separate word for that.

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

The neutral order here is:

• Цикл стирки начнётся завтра.

But you could also say:

• Завтра начнётся цикл стирки.
• Начнётся завтра цикл стирки. (less neutral, more stylistic)

The meaning stays basically the same, but the focus changes:

• Цикл стирки начнётся завтра = neutral statement
• Завтра начнётся цикл стирки = emphasizes tomorrow

English is much less flexible here.

Because завтра here is an adverb, meaning tomorrow.

Adverbs do not change for case, gender, or number.
It simply tells you when the action happens:

• начнётся когда? — завтра
• will begin when? — tomorrow

So завтра stays the same.

Yes, it is understandable and natural, especially in appliance or laundry contexts.

Depending on context, Russian speakers might also say things like:

• режим стирки = wash mode / washing setting
• программа стирки = wash program
• стирка начнётся завтра = the washing will start tomorrow

But цикл стирки is a good direct equivalent of wash cycle.

Because the subject is цикл, which is singular.

Even though стирки follows it, стирки is not the subject. It is just a genitive noun describing цикл.

So the grammatical subject is:

• цикл = singular masculine noun

That is why the verb is also singular:

• цикл ... начнётся

If the subject were plural, the verb would change:

• Циклы стирки начнутся завтра. = The wash cycles will begin tomorrow.

Not in the same natural way here.

• начнётся is perfective simple future and means will begin
• будет начинаться is imperfective compound future and would sound more like will be beginning / will start happening, which is usually less natural here

For a single event beginning at a specific time, Russian strongly prefers the perfective:

• Цикл стирки начнётся завтра.

So this is the normal choice.

A very literal translation would be:

• The cycle of washing will begin tomorrow.

A more natural English translation is:

• The wash cycle will start tomorrow.

This difference is useful because Russian often uses noun + genitive noun, where English often uses a more compact noun phrase.