Дочка выбрала пончик, потому что у него была яркая посыпка.

Both mean daughter, but дочка is the more affectionate, everyday form. Дочь is the basic dictionary form and can sound a little more neutral or formal.

So:

• дочь = daughter
• дочка = daughter / little daughter / dear daughter, depending on context

In normal conversation, дочка is very common.

Because the subject is дочка, which is feminine singular, and the verb is in the past tense.

In Russian past tense, verbs agree with the subject in gender and number:

• выбрал = he chose
• выбрала = she chose
• выбрало = it chose
• выбрали = they chose

So дочка выбрала means the daughter chose.

This is a question of verbal aspect.

• выбрала is perfective: she chose, meaning the action was completed and there was a result.
• выбирала is imperfective: she was choosing or used to choose, focusing on the process rather than the completed choice.

In this sentence, the daughter made a choice and picked the donut, so the perfective выбрала is the natural form.

Here пончик is the direct object, so it is in the accusative case. But for masculine inanimate nouns, the accusative singular is usually the same as the nominative.

So:

• nominative: пончик
• accusative: пончик

If it were a masculine animate noun, the form would usually change differently.

Because потому что introduces a subordinate clause, like because in English.

The sentence has two parts:

• Дочка выбрала пончик
• потому что у него была яркая посыпка

Russian normally puts a comma before потому что.

Потому что means because.

It introduces the reason for something:

• Она ушла, потому что устала. = She left because she was tired.
• Дочка выбрала пончик, потому что у него была яркая посыпка. = The daughter chose the donut because it had bright sprinkles.

A learner sometimes notices потому by itself, but потому что is the full conjunction meaning because.

Russian very often expresses possession with у + genitive + быть rather than with a verb like to have.

So у него была яркая посыпка literally means something like:

• by it there was bright topping

But in natural English, that becomes:

• it had bright sprinkles
• it had a bright topping

This possession pattern is extremely common in Russian:

• У меня есть книга. = I have a book.
• У него была машина. = He had a car.

Yes, него can mean him, but it can also refer to a masculine noun that is not a person.

The noun пончик is grammatically masculine, so the pronoun is also masculine:

• пончик → он
• у него = of it / on its side / it had, depending on context

In English we usually say it, but Russian follows grammatical gender more strongly. Since пончик is masculine, Russian uses the masculine pronoun.

Also, after у, the pronoun must be in the genitive case, so он becomes него.

Because посыпка is a feminine singular noun.

That affects both the verb and the adjective:

• была is feminine singular past tense of быть
• яркая is feminine singular form of яркий
• посыпка is feminine singular

So all three match:

• яркая посыпка была

Russian agreement is very important: adjectives and past-tense verbs often change to match the noun.

Посыпка means a topping that is scattered over food, especially small sweet decorations like sprinkles.

For a donut, яркая посыпка most naturally suggests colorful sprinkles or a bright decorative topping.

A useful thing to notice is that Russian uses посыпка as a singular noun, while English often prefers the plural sprinkles.

So:

• яркая посыпка = bright sprinkles / a bright topping

Yes, Russian word order is more flexible than English, but the given order is natural and neutral.

• Дочка выбрала пончик, потому что у него была яркая посыпка.

This sounds like a normal statement: first the action, then the reason.

You could change the word order for emphasis, but that would shift the focus and may sound less neutral. For example, moving яркая or у него around might emphasize the topping more strongly.

So for a learner, the given word order is a good standard model to remember.