Neměl bys dávat moc soli a pepře do polévky.

Neměl bys + infinitive is a very common Czech way to say you shouldn't + verb.

• měl bys = you should
• neměl bys = you shouldn't

Even though it is built from the verb mít (to have), learners should usually treat měl bys / neměl bys as a fixed pattern meaning should / shouldn't.

So:

• Neměl bys dávat... = You shouldn't put/add...

Because in Czech, this form shows the gender of the person being addressed.

• to a man or boy: Neměl bys
• to a woman or girl: Neměla bys

So this sentence is addressed to one male person.

If you were speaking to a female, it would be:

• Neměla bys dávat moc soli a pepře do polévky.

This is very different from English, where you does not show gender.

bys is the 2nd person singular conditional auxiliary. It is part of how Czech forms meanings like would and should.

In this sentence:

• měl bys = literally the conditional structure for you should
• bys tells you the subject is you singular

A useful thing to remember: bys is the normal standard form here. Native speakers may sometimes say nonstandard variants in casual speech, but learners should use bys.

Because Czech usually leaves out subject pronouns when they are already clear from the verb form.

Here, bys already tells you the sentence means you singular, so ty is unnecessary.

• natural: Neměl bys dávat...
• with extra emphasis: Ty bys neměl dávat...

Adding ty can sound emphatic, contrastive, or slightly emotional, depending on context.

This is about aspect, which is very important in Czech.

• dávat = imperfective
• dát = perfective

Here dávat is used because the sentence gives general advice or talks about a repeated/ongoing kind of action:

• Neměl bys dávat moc soli a pepře do polévky. = You shouldn't be putting too much salt and pepper in soup / You shouldn't add too much salt and pepper.

If you used dát, it would sound more like one specific completed act:

• Neměl bys dát moc soli a pepře do polévky. = You shouldn't put too much salt and pepper into the soup this one time.

So dávat fits broad advice better.

Because after moc in this meaning, Czech normally uses the genitive case.

Base forms:

• sůl = salt
• pepř = pepper

Genitive forms:

• soli
• pepře

So:

• moc soli a pepře = a lot of / too much salt and pepper

This is very common in Czech after quantity words and expressions.

Here moc means a lot of / much because it is used with nouns.

• moc soli = a lot of salt

In this negative advice sentence, English usually translates that more naturally as too much:

• Neměl bys dávat moc soli... = You shouldn't add too much salt...

Important distinction:

• moc
  • noun = a lot of / much
• moc
  • adjective/adverb = very / too

Examples:

• moc soli = a lot of salt
• moc slaný = too salty / very salty, depending on context

If Czech wanted to be more explicitly formal or emphatic about too much, it could also use příliš or příliš mnoho.

Because do means into and it takes the genitive case.

• polévka = soup
• do polévky = into the soup

So polévky is the genitive singular form of polévka.

This matches the idea of adding something into the soup.

Compare:

• do polévky = into the soup
• v polévce = in the soup

So in this sentence, do polévky is the natural choice because it describes putting salt and pepper into it.

Yes. It is addressed to one person informally.

• Neměl bys... = informal singular, to one male
• Neměla bys... = informal singular, to one female

Polite singular:

• to a man: Neměl byste dávat...
• to a woman: Neměla byste dávat...

Plural:

• Neměli byste dávat... for a group with at least one male or mixed gender
• Neměly byste dávat... for an all-female group

So the original sentence is definitely the informal you.

Yes, Czech word order is flexible, but not completely free.

The original order is neutral and natural:

• Neměl bys dávat moc soli a pepře do polévky.

You could also say:

• Do polévky bys neměl dávat moc soli a pepře.

That version puts more emphasis on do polévky.

One important thing: bys is a clitic, so it usually likes to stay near the beginning of the sentence, typically in second position. That is why Czech word order changes are possible, but some placements sound much more natural than others.

So yes, the order can change, but the original sentence is a very good default model.

Normally it means that the person should not add too much of these seasonings — effectively too much salt and too much pepper.

Czech allows one moc to cover both nouns joined by a:

• moc soli a pepře

English often works the same way:

• too much salt and pepper

So you do not need to repeat moc before both nouns unless you want special emphasis.