Pro mě je polévka v zimě nejlepší jídlo.

Pro mě literally means “for me.”

The preposition pro (“for”) always takes the accusative case.
The pronoun já (“I”) in the accusative is mě (or the more formal mne).

So:

• pro + accusative → pro mě / pro mne = for me

They are different case forms of já (“I”):

• mě / mne = genitive or accusative
• mně = dative or locative

In this sentence we need the accusative after pro, so we choose mě or mne.

Usage:

• mě – normal, everyday spoken Czech
• mne – more formal, literary, or emphatic
• mně – never after pro; it is used after prepositions that take dative/locative (e.g. k mně, o mně)

So pro mě is the standard colloquial choice here; pro mne would also be correct, just more formal.
Pro mně is grammatically wrong.

No. After a preposition, Czech almost never uses the nominative form of pronouns.

• já is nominative (subject form: I)
• After pro, we must use the accusative → mě / mne

So:

• ✅ pro mě / pro mne
• ❌ pro já

It is not grammatically necessary; it is word order for emphasis.

Putting Pro mě first highlights your personal opinion:

• Pro mě je polévka v zimě nejlepší jídlo.
  → For me, soup is the best food in winter (personally speaking).

You could also say:

• Polévka je pro mě v zimě nejlepší jídlo.
• V zimě je pro mě polévka nejlepší jídlo.

All are correct; the choice mainly changes what is emphasized:

• At the beginning of the sentence → strongest emphasis.
  Here, you are emphasizing “for me”.

V zimě uses the locative case of zima (“winter”).

The preposition v (“in”) usually takes:

• locative when it means location or time inside something
  
  • v Praze (in Prague)
  • v zimě (in winter)

Declension of zima (feminine, singular):

• nominative: zima (winter)
• genitive: zimy
• dative: zimě
• accusative: zimu
• locative: zimě
• instrumental: zimou

So with v in the sense “in (during) winter”, we must use locative: v zimě, not v zima or v zimu.

No.

• v zimu – uses accusative, wrong here
• v zimou – uses instrumental, also wrong here

For time and place “in/inside” with v, you use locative:

• v zimě – in winter
• v létě – in summer
• v noci – at night

So only v zimě is correct in this meaning.

Polévka is in the nominative singular, because it is the subject of the sentence:

• Polévka je v zimě nejlepší jídlo.
  → Soup is the best food in winter.

Case summary:

• Subject → nominative → polévka
• Direct object → accusative → polévku (e.g. Jím polévku. – I eat soup.)
• Indirect object / location etc. → other cases (polévce, etc.) depending on the preposition or verb.

Here, polévka is not an object, it’s what we are talking about, so nominative is correct.

With the verb být (“to be”), when you say “X is Y”, both X and Y are in the nominative:

• Polévka (subj.) je nejlepší jídlo (predicate nominative).

This is similar to:

• On je učitel. – He is a teacher.
  (both on and učitel in nominative)

So the structure is:

• [Polévka]NOM je [nejlepší jídlo]NOM.

There is no article in Czech, so jídlo can mean “a food / a dish / the food” depending on context.

Yes. The degrees of comparison are:

• dobrý – good
• lepší – better
• nejlepší – best

Nejlepší is the superlative (“the best”).
It belongs to the -í adjective type (like cizí – foreign), so in nominative singular it has the same form for all genders:

• nejlepší polévka (feminine) – the best soup
• nejlepší jídlo (neuter) – the best food
• nejlepší film (masculine inanimate) – the best film

In other cases it changes (e.g. nejlepšího, nejlepšímu), but in this sentence nominative singular is used, so it stays nejlepší.

Adding to is very common and sounds slightly more emphatic:

• Pro mě je polévka v zimě nejlepší jídlo.
• Pro mě je polévka v zimě to nejlepší jídlo.

Both are correct and natural. The version with to:

• feels a bit more like “the best possible food”,
• makes the predicate stand out: to nejlepší jídlo = that best food.

In everyday speech, many speakers actually prefer “to nejlepší jídlo” in this kind of “X is the best Y” sentence.

Yes, very natural alternatives are:

• V zimě mám nejradši polévku.
  → In winter I like soup the most.
• Polévka je moje nejoblíbenější jídlo v zimě.
  → Soup is my favourite food in winter.

Differences:

• Pro mě je polévka v zimě nejlepší jídlo.
  – a bit more objective: “for me, soup is the best food in winter.”
• Mám nejradši polévku.
  – clearly about personal liking (“I like it the most”).

All are correct; it’s just a stylistic choice.

Czech has no articles (no a/an or the).

So:

• polévka can mean “soup”, “a soup”, or “the soup”,
• jídlo can be “food”, “a dish”, or “the food”.

The exact English translation depends on context, not on extra words in Czech.
Here, natural English is:

• For me, soup is the best food in winter.

Approximate pronunciation (slashes = phonemes, stress always on the first syllable):

• Pro – /pro/
• mě – /mje/ (similar to “mye”)
• je – /jɛ/ (“ye”)
• polévka – /ˈpolɛːfka/ (PO-layf-ka, long é)
• v – /v/ (often merges with next word in fast speech)
• zimě – /ˈzɪmɲɛ/ (ZIM-nye)
• nejlepší – /ˈnɛjlɛpʃiː/ (NAY-lep-shee, long í)
• jídlo – /ˈjiːdlɔ/ (YEE-dlo, long í)

Spoken slowly:
[Pro mě] [je] [polévka] [v zimě] [nejlepší] [jídlo].