На завтрак я взял йогурт, абрикос и чашку тёплого чая.

На завтрак means for breakfast.

In Russian, на is commonly used with meals in expressions like:

• на завтрак — for breakfast
• на обед — for lunch
• на ужин — for dinner

So На завтрак я взял... is a very natural way to say For breakfast, I took/had...

It sets the context first, much like English For breakfast, ...

Взял is the past tense masculine singular form of взять.

• взять = infinitive, to take
• взял = took

Russian past tense changes for gender:

• я взял — I took, if the speaker is male
• я взяла — I took, if the speaker is female

Also, взять is perfective, so it presents the action as a completed whole: I took / I chose / I got.

Compare:

• я взял йогурт — I took/got a yogurt
• я брал йогурт — I was taking / used to take / took (imperfective, less natural here)

In this sentence, the completed action is the normal choice.

In Russian, я itself does not show gender, but the past tense verb does.

So the verb tells you the speaker’s gender:

• я взял — the speaker is male
• я взяла — the speaker is female

This is very common in Russian past tense.

Because чашку is the accusative singular form of чашка.

Here, чашку is a direct object of взял:

• взял что? — took what?
• чашку — a cup

For many feminine nouns ending in -а, the accusative singular changes to -у:

• чашка → чашку
• книга → книгу
• лампа → лампу

So:

• чашка = a cup
• взял чашку = took a cup

Because йогурт and абрикос are masculine inanimate nouns, and in Russian their accusative singular is usually the same as the nominative singular.

So:

• йогурт → йогурт
• абрикос → абрикос

But чашка is feminine, so its accusative changes:

• чашка → чашку

This is a very important pattern:

• masculine inanimate: often no change in the accusative singular
• feminine in -а / -я: usually changes in the accusative singular

Because after a container word like чашка (cup), Russian often uses the thing inside in the genitive case.

So:

• чашка чая — a cup of tea
• чашка кофе — a cup of coffee
• бутылка воды — a bottle of water

That is why you get:

• чашку тёплого чая — a cup of warm tea

Here:

• чашку is accusative, because it is the direct object
• тёплого чая is genitive, because it depends on чашку and means of warm tea

If you were talking directly about the tea itself as the object, you could say:

• Я взял тёплый чай. — I took warm tea.

But with a cup of..., Russian uses the genitive for the contents.

Because the adjective must match the noun it describes.

Here, тёплого describes чая, and чая is genitive singular. So the adjective must also be genitive singular:

• тёплый чай — warm tea
• тёплого чая — of warm tea

This is standard adjective agreement in Russian: adjectives change for gender, number, and case.

Чая is the genitive singular of чай.

• nominative: чай
• genitive: чая

It appears here because of the expression чашка чая — a cup of tea.

So in the full phrase:

• чашку = accusative singular
• тёплого чая = genitive singular

Yes. Russian word order is fairly flexible.

This sentence begins with На завтрак to set the scene first. That is very natural. But other orders are possible, for example:

• Я взял на завтрак йогурт, абрикос и чашку тёплого чая.
• Йогурт, абрикос и чашку тёплого чая я взял на завтрак.

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

The original order is natural because it starts with the context (for breakfast) and then gives the items.

Because the sentence is talking about one apricot.

In Russian, singular and plural work much like in English here:

• абрикос — an apricot
• абрикосы — apricots

So if the person took more than one, you would need the plural form, for example:

• я взял абрикосы — I took apricots

Because Russian punctuation in a list works much like English punctuation in a simple series:

• item 1, item 2, and item 3

So:

• йогурт, абрикос и чашку тёплого чая

The comma separates the earlier items in the list, and и means and before the final item.

Russian normally does not use a serial comma before и in this kind of list, so the punctuation here is exactly what you would expect.

It can suggest several close ideas depending on context.

In a food context, взял often means something like:

• took
• got
• chose
• sometimes even had in a loose English translation

For example, in a cafeteria or buffet situation:

• Я взял йогурт... = I took/got/chose a yogurt...

So even if the English translation you were shown uses had or ate, the Russian verb still literally means took. Russian often describes the selection of food this way.