На обед я приготовил суп из чечевицы, потому что дома не было мяса.

На обед is a very common Russian expression meaning for lunch or as lunch.

Here на is used in a set phrase with meals:

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

So На обед я приготовил... means For lunch, I made...

Using для обеда would sound less natural here. Для usually means for the purpose of or intended for, but with meals Russian normally uses на.

Russian past tense agrees with the gender and number of the subject.

The verb here is приготовил, which is:

• past tense
• singular
• masculine

So this tells us the speaker is male: I prepared / I cooked.

Compare:

• я приготовил = I prepared, said by a man
• я приготовила = I prepared, said by a woman
• мы приготовили = we prepared

Приготовил is perfective, while готовил is imperfective.

• готовил focuses on the process: was cooking, used to cook, cooked
• приготовил focuses on the completed result: cooked / prepared successfully

In this sentence, the speaker means that the soup was actually made as a finished meal, so приготовил is the natural choice.

After из meaning from / made of, Russian normally uses the genitive case.

So:

• чечевица = lentil / lentils
• из чечевицы = from lentils, made of lentils

That is why чечевица changes to чечевицы.

This pattern is very common:

• сок из яблок = juice from apples
• салат из овощей = salad made of vegetables
• суп из чечевицы = lentil soup

Russian often uses a singular noun where English uses a plural or a mass noun.

Чечевица is commonly treated as a mass noun meaning lentils as a food ingredient. So суп из чечевицы is the normal way to say lentil soup.

This is not unusual across languages: the way a food is counted does not always match English.

Потому что means because.

It introduces the reason:

• Я приготовил суп из чечевицы, потому что дома не было мяса.
• I made lentil soup because there was no meat at home.

Yes, it is a very common and standard way to say because in everyday Russian.

You may also see так как, which is more formal or written:

• Так как дома не было мяса, я приготовил суп из чечевицы.

This is a very common point of confusion.

Дом means house or home. But дома can also function as an adverb meaning at home.

So in this sentence:

• дома не было мяса = there was no meat at home

This дома is not the plural nominative houses. It is a fixed adverbial form meaning at home.

Compare:

• Я дома = I am at home
• Мы были дома = We were at home

Russian often uses an impersonal structure to express existence or absence:

• было мясо = there was meat
• не было мяса = there was no meat

This is more natural than making meat the subject.

So дома не было мяса literally works like:

• At home there was not meat

In natural English:

• There was no meat at home

This pattern is extremely common:

• В магазине не было хлеба = There was no bread in the store
• На столе не было книги = There was no book on the table

After не было, Russian usually puts the thing that is absent into the genitive case.

So:

• мясо = meat
• мяса = of meat / any meat

That is why we get:

• не было мяса = there was no meat

This is part of a larger pattern with negated existence:

• был суп = there was soup
• не было супа = there was no soup

For learners, it is useful to remember не было + genitive as a common structure.

Yes, it can often be omitted, because the verb form already shows the person.

• На обед я приготовил суп...
• На обед приготовил суп...

Both are possible.

Including я adds clarity or emphasis. It can help highlight that I was the one who cooked it.

Russian often omits subject pronouns when they are obvious from the verb, but speakers still use them when they want emphasis, contrast, or simply a natural conversational rhythm.

Russian word order is flexible, and the beginning of the sentence often shows what the speaker wants to frame first.

Starting with На обед emphasizes the context:

• As for lunch / For lunch...

So the sentence first sets the scene, then says what happened:

• For lunch, I made lentil soup...

A more neutral order is also possible:

• Я приготовил на обед суп из чечевицы...

The original version sounds very natural because it introduces the meal first.

Yes, but it is a bit heavier and less simple than потому что.

• потому что дома не было мяса = because there was no meat at home
• из-за того, что дома не было мяса = because of the fact that there was no meat at home

The second version can sound more formal, more emphatic, or sometimes slightly more focused on an unfavorable cause. In everyday speech, потому что is usually the best choice here.

It is one very natural and standard way.

You may also hear:

• чечевичный суп

This is an adjective-based version:

• чечевичный = lentil

So both are possible:

• суп из чечевицы
• чечевичный суп

The first literally means soup made from lentils.
The second means lentil soup using an adjective. Both are correct and natural.

The sentence breaks down like this:

• На обед = for lunch
• я приготовил = I prepared / cooked
• суп из чечевицы = lentil soup, soup made from lentils
• потому что = because
• дома не было мяса = there was no meat at home

So the overall pattern is:

[time/purpose phrase] + [subject] + [completed action] + [object] + because + [reason]

This is a very useful sentence model for everyday Russian.