Ты хочешь что-нибудь поесть?

Ты means you when speaking to one person informally.

Хочешь is the 2nd person singular form of хотеть = to want.

So Ты хочешь literally means you want, and in a question it means do you want. Russian does not need an extra word like do to make a question.

Yes. Ты is the informal singular form of you.

You use it with:

• friends
• family
• children
• people you know well

If you want to be polite or formal, or if you are speaking to more than one person, you would say:

Вы хотите что-нибудь поесть?

Yes. Russian often drops subject pronouns when the meaning is clear from the verb form.

So Хочешь что-нибудь поесть? is also completely natural.

Including ты can make the sentence feel a bit more personal, direct, or contrastive, depending on context.

Russian usually makes yes/no questions with:

• intonation
• sometimes word order
• a question mark in writing

So Ты хочешь что-нибудь поесть? is understood as a question without any extra helper word.

English needs Do you want... ?
Russian just uses Ты хочешь... ?

Что-нибудь means something or anything, depending on context.

In this sentence, it means something like something to eat / anything to eat.

It is built from:

• что = what
• -нибудь = a particle that makes it indefinite

So it gives the idea of some unspecified thing.

Both can often translate as something, but the nuance is different.

Что-нибудь is especially common in:

• questions
• offers
• suggestions
• situations where any option is fine

That makes it very natural in Ты хочешь что-нибудь поесть?

Что-то is more common when the speaker has some vague but more concrete thing in mind, especially in statements.

So:

• Хочешь что-нибудь поесть? = Do you want something/anything to eat?
• Хочешь что-то поесть? = possible, but a bit less neutral in nuance

-Нибудь is a particle used with question words to make indefinite words.

Examples:

• кто-нибудь = someone / anyone
• где-нибудь = somewhere / anywhere
• когда-нибудь = sometime / ever

It is normally written with a hyphen, so что-нибудь is the correct spelling.

Поесть is the perfective infinitive. In everyday Russian, it usually means to have something to eat or to eat (on one occasion).

It sounds very natural when talking about a specific eating event, like offering someone food now.

Есть is the imperfective verb and is more general:

• to eat
• to be eating
• to eat in general / habitually

So:

• Ты хочешь поесть? = Do you want to eat / have something to eat?
• Ты хочешь есть? = also possible, often closer to Are you hungry? / Do you want to eat?

Sometimes the prefix по- can give the sense of doing something for a while or a bit, but with поесть the usual everyday meaning is simply have something to eat.

It does not necessarily mean only a tiny amount. It is just a very common, natural verb for a single meal or eating occasion.

Russian word order is flexible.

The phrase что-нибудь поесть is very common and works a lot like English something to eat.

You can also hear:

• Ты хочешь поесть что-нибудь?

But что-нибудь поесть is a very natural order and sounds idiomatic.

Yes, absolutely.

Ты хочешь поесть? means Do you want to eat?

Adding что-нибудь makes the idea of something to eat more explicit. It often sounds more like an offer of food or a snack.

So:

• Ты хочешь поесть? = Do you want to eat?
• Ты хочешь что-нибудь поесть? = Do you want something to eat?

In this sentence, что-нибудь is the most straightforward and idiomatic form, especially in the pattern что-нибудь поесть = something to eat.

You may also hear чего-нибудь in colloquial Russian, especially when the idea is more like some food / a bit of something. That is a more advanced nuance involving the genitive.

For a learner, the important thing is:

• что-нибудь поесть is correct and very natural
• чего-нибудь is also something you may hear later, but it is not necessary to use at first

You would say:

Вы хотите что-нибудь поесть?

Changes:

• ты → вы
• хочешь → хотите

This can mean either:

• Do you want something to eat? to one person politely
• Do you all want something to eat? to several people