Brambory s olejem a pepřem nejsou špatné, ale já mám raději rýži.

Because brambory means potatoes, which is the plural form of brambora (potato).

In this sentence, brambory is the subject, so it is in the nominative plural:

• brambora = a potato
• brambory = potatoes

Czech often uses the plural here the same way English does when talking about a food dish: Potatoes with oil and pepper...

Because after the preposition s meaning with, Czech normally uses the instrumental case.

So:

• olej → olejem
• pepř → pepřem

That is why you get:

• s olejem = with oil
• s pepřem = with pepper

This is a very important pattern:

• s + instrumental

For the same reason: s requires the instrumental case.

When one s applies to two nouns joined by a (and), both nouns usually go into the instrumental:

• s olejem a pepřem

So the structure is:

• s + instrumental noun + a + instrumental noun

Because nejsou is the 3rd person plural form of být (to be) in the present tense, and the subject brambory is plural.

So:

• je = is
• jsou = are
• není = is not
• nejsou = are not

Since the sentence says potatoes ... are not bad, Czech uses nejsou.

Because špatné is an adjective agreeing with brambory.

In this sentence, špatné means bad, and it must match the subject in number and gender pattern. Brambory is plural, and it is not masculine animate, so the standard adjective ending here is -é:

• špatné

Compare:

• brambory nejsou špatné = the potatoes are not bad

This is normal agreement after být (to be).

Mít raději is a common Czech way to say to prefer.

So:

• mám rád / ráda = I like
• mám raději = I prefer / I like better

In this sentence:

• já mám raději rýži = I prefer rice

The word raději by itself has the sense of rather / more willingly / preferably, but in the expression mít raději, the whole phrase means to prefer.

Because rýže is the dictionary form, but here the word is the direct object of mám raději, so it goes into the accusative case.

So:

• rýže = nominative
• rýži = accusative

That is why Czech says:

• mám raději rýži = I prefer rice

This is a very useful pattern:

• mít rád / mít raději + accusative

Yes, it could.

Czech often leaves out subject pronouns because the verb already shows the person:

• mám already means I have / I like / I prefer

So:

• mám raději rýži = I prefer rice

Adding já gives extra emphasis or contrast. Here it sounds like:

• ...but I prefer rice

So the já is not required for grammar; it is there for emphasis.

Yes. Czech word order is more flexible than English word order.

This sentence uses a very natural, neutral order:

• Brambory s olejem a pepřem nejsou špatné, ale já mám raději rýži.

But Czech can move things around for emphasis. For example:

• Ale já mám raději rýži.
• Ale rýži mám raději já.
  This would sound more contrastive or emphatic.

So word order in Czech often helps show what is new, contrasted, or emphasized.

Because ale means but, and in Czech it is normally preceded by a comma when it connects clauses.

So:

• ..., ale ...

This is very similar to English:

• ..., but ...

So the comma here is standard Czech punctuation.

Because Czech has no articles.

English distinguishes:

• a potato
• the potato
• rice
• the rice

Czech usually does not use separate words for this. Context tells you whether something is general, specific, or indefinite.

So:

• brambory can mean potatoes, the potatoes, or sometimes just potato dish, depending on context
• rýži can mean rice or the rice, depending on context

This is one of the biggest differences from English.

Because the two foods are being treated differently as nouns.

Brambory is normally a plural count noun when talking about potatoes as food:

• brambory = potatoes

Rýže is usually an uncountable mass noun, like rice in English:

• rýže = rice

So Czech matches English quite closely here:

• potatoes
• rice

Yes, ř is one of the hardest Czech sounds for English speakers.

In pepřem, the word is roughly pronounced something like:

• pep-rzhem
  but that is only an approximation

The sound ř is a special Czech sound, something between r and zh (like the s in measure). In careful speech:

• pepř = pepper
• pepřem = with pepper

If you cannot say ř perfectly yet, a closer r or zh-like approximation is often understandable, but learners usually work on this sound over time.

They are very close in meaning.

• raději is the standard form
• radši is a common colloquial form in spoken Czech

So:

• Mám raději rýži. = standard
• Mám radši rýži. = common in everyday speech

Both mean I prefer rice, but raději is the more neutral form for learners to remember first.