Měl bys číst recept pomalu, aby v polévce nebylo moc soli.

Měl bys is a very common Czech way to say you should or you ought to.

Grammatically, it comes from the verb mít and uses a conditional form: měl + bys

In modern Czech, this structure is often used to give advice or a recommendation: Měl bys číst = You should read

In this sentence, měl shows that the speaker is talking to one male person informally. If you were talking to a woman, it would be Měla bys.

bys is a clitic, which means it usually goes in the second position of the clause.

So Czech naturally says: Měl bys číst...

Not normally: Měl číst bys...

If you add the subject pronoun for emphasis, the order can change: Ty bys měl číst...

That is because bys still wants to be near the beginning of the clause.

Czech often drops subject pronouns when they are already clear from the verb form.

Here, bys already tells you that the subject is you singular, so ty is unnecessary.

That is very normal in Czech. Adding ty would usually sound more emphatic: Ty bys měl číst recept pomalu... This can suggest contrast, emphasis, or mild insistence.

After měl bys, the main action verb stays in the infinitive.

So: měl bys číst = you should read

This is similar to other Czech verb patterns: musíš číst = you must read můžeš číst = you can read

Once the first verb carries the person and mood, the second verb usually stays in its basic infinitive form.

Because recept is the direct object of číst.

You are reading what?
recept

That means it should be in the accusative. But recept is a masculine inanimate noun, and in the singular its accusative form is the same as its nominative form.

So: recept = nominative singular
recept = accusative singular

That is why the form does not visibly change.

Because the sentence needs an adverb, not an adjective.

pomalu describes how you should read: čit pomalu = to read slowly

The adjective is pomalý = slow, but adjectives describe nouns: pomalý člověk = a slow person

So: pomalý = adjective
pomalu = adverb

English works the same way: slow vs slowly

aby introduces a purpose clause. In English, it often means so that or in order that.

So: Měl bys číst recept pomalu, aby... means: You should read the recipe slowly, so that...

The second clause explains the intended result or purpose of the first one.

abys does exist, but it is used when the subordinate clause has you as its grammatical subject in a personal form.

For example: Říkám to, abys tomu rozuměl. = I’m saying it so that you understand it.

In your sentence, the clause is not built around you doing something. Instead, it is an impersonal/existential idea: aby v polévce nebylo moc soli = so that there wouldn’t be much / too much salt in the soup

Because of that, plain aby is the correct form here.

The preposition v means in, and when it expresses location, it takes the locative case.

The noun is: polévka = soup

Its locative singular is: v polévce = in the soup

So this is simply the normal case required after v when you mean location.

Because after quantity words like moc, Czech usually uses the genitive.

So: moc soli = a lot of salt / much salt

The basic form is: sůl = salt

Its genitive singular is: soli

This pattern is very common: hodně vody = a lot of water
málo času = little time
moc práce = a lot of work

No. Here moc means much / a lot of because it is used with a noun: moc soli = a lot of salt

Czech moc can also mean very, but then it usually goes with adjectives or adverbs: moc dobrý = very good
moc pomalu = very slowly

So the meaning depends on what follows it.

In this sentence, English may naturally translate it as too much salt, because the clause describes an unwanted result that the speaker wants to avoid.

This is a very common question.

In sentences with quantity expressions like moc soli, Czech often uses third-person singular neuter in an existential structure:

Bylo tam hodně lidí. = There were a lot of people there.
Nebylo moc času. = There wasn’t much time.

So: v polévce nebylo moc soli

This does not work like a simple sentence where sůl is the straightforward subject. Instead, the whole phrase moc soli behaves like a quantity expression, and Czech normally uses bylo / nebylo with that pattern.

That is why nebylo sounds natural here.

Yes. Czech word order is fairly flexible, and changing it usually changes emphasis rather than basic meaning.

The given order: Měl bys číst recept pomalu, aby v polévce nebylo moc soli. is a normal, neutral version.

But other orders are possible, for example: Recept bys měl číst pomalu... This puts more focus on recept.

Or: Měl bys pomalu číst recept... This gives pomalu a slightly different emphasis.

So the sentence you have is not the only possible order, but it is perfectly natural.