Nauka historii pomaga mi zrozumieć przeszłość.

Here nauka means learning or the study of something, not science.

So nauka historii means learning history or the study of history.

This word can have more than one meaning in Polish:

• nauka = learning, studying
• nauka = science

The context tells you which meaning is intended. In this sentence, because it is followed by historii, it clearly means learning/studying history.

Because nauka is followed by the genitive case.

The basic form is:

• historia = history

But after nauka, Polish normally uses the genitive:

• nauka historii = learning/study of history

So:

• historia → nominative
• historii → genitive singular

This is very common in Polish with nouns that express studying, learning, teaching, etc.

Because the verb pomagać takes the dative case for the person being helped.

So:

• mi = to me
• mnie = me

In this sentence, the meaning is helps me, but grammatically in Polish it is closer to helps to me, so the dative is used:

• pomaga mi = helps me

Compare:

• On pomaga mi. = He helps me.
• To pomaga dzieciom. = This helps children.

Mi is the unstressed short form and is very natural here.

Because Polish often uses pomagać + someone + infinitive to mean helps someone do something.

So:

• pomaga mi zrozumieć przeszłość = helps me understand the past

This structure is very normal:

• pomaga mi pracować = helps me work
• pomaga nam uczyć się = helps us learn

So zrozumieć is not conjugated because it works like to understand after helps.

This is a question of aspect, which is very important in Polish.

• rozumieć = to understand, to be understanding (imperfective)
• zrozumieć = to understand, to come to understand, to grasp fully (perfective)

In this sentence, zrozumieć fits well because the idea is that studying history helps you reach understanding of the past.

So:

• rozumieć przeszłość = to understand the past
• zrozumieć przeszłość = to come to understand the past / to fully understand the past

Both can make sense in some contexts, but zrozumieć sounds very natural here because it emphasizes achieving understanding.

Because przeszłość is the direct object here, and its accusative singular has the same form as the nominative singular.

So:

• przeszłość = the past
• zrozumieć przeszłość = to understand the past

Not all feminine nouns change in the accusative. Many feminine nouns ending in -a do:

• książka → książkę

But nouns like przeszłość (ending in -ość) often keep the same form in nominative and accusative singular:

• przeszłość → przeszłość

Yes.

The sentence structure is:

• Nauka historii = subject
• pomaga = verb
• mi = indirect object
• zrozumieć przeszłość = infinitive phrase/complement

So literally it is:

• The study of history helps me understand the past.

Since nauka is singular, the verb is also singular:

• pomaga = helps

Yes, Polish word order is fairly flexible, although some orders sound more natural than others.

The original sentence:

• Nauka historii pomaga mi zrozumieć przeszłość.

Possible alternatives:

• Nauka historii pomaga zrozumieć mi przeszłość.
  This is possible, but less natural.
• Mi pomaga nauka historii zrozumieć przeszłość.
  Grammatically possible in a marked context, but not the most neutral order.

The original version is the most natural and neutral.

Polish often changes word order for:

• emphasis
• contrast
• style

But for learners, the original order is the best one to use.

Yes, you could, but there is a small difference in feel.

• nauka historii = study/learning of history; a broad, natural phrase
• uczenie się historii = learning history; more focused on the process of learning

So both can work:

• Nauka historii pomaga mi zrozumieć przeszłość.
• Uczenie się historii pomaga mi zrozumieć przeszłość.

The first one sounds a bit more polished and general. The second one emphasizes the act of learning more directly.

A rough guide:

• zrozumieć ≈ zro-ZOO-myech
• przeszłość ≈ pshe-SHWOHSHCH

A few useful pronunciation notes:

• rz usually sounds like zh (like the s in measure), though in prze- it combines with nearby sounds in a way that can be tricky for learners
• sz sounds like sh
• ś/si sounds like a softer sh
• ć/ci sounds like a soft ch
• ł sounds like English w

So:

• przeszłość has several Polish sounds packed together, which makes it hard at first
• zrozumieć has stress on -mieć? Actually Polish stress is usually on the second-to-last syllable, so here the stress is on -mie-: zro-ZU-mieć? More accurately, zro-ZU-mieć is not right either if counted carelessly; the stress is on the penultimate syllable: zro-ZU-mieć if pronounced in three syllables, but many learners hear the -mieć ending as one unit. The key rule to remember is: stress the second-to-last syllable.

The most important thing is not to worry about being perfect immediately—Polish consonant clusters take practice.

Yes, in meaning, but not as a separate word.

In English you say:

• helps me understand

Not:

• helps me to understand only, although that is also possible in English

Polish works similarly:

• pomaga mi zrozumieć = helps me understand

There is no separate word for to before the infinitive here. The infinitive zrozumieć already carries the to understand meaning.

Mi is the dative singular form of ja (I).

Some common forms are:

• ja = I
• mnie / mnie = me
• mi = to me
• mną = with me

In this sentence:

• pomaga mi = helps me

A useful thing to remember:

• mi is usually the short, unstressed form
• mnie is often used for emphasis or after prepositions

Examples:

• On mi pomaga. = He helps me.
• Dla mnie to ważne. = For me, that is important.

So in your sentence, mi is exactly the form you would expect.