Když má můj syn hlad, měla by mu maminka dát banán nebo pomeranč.

Když means when in the sense of a general situation or condition.

So:

• Když má můj syn hlad = When my son is hungry

In Czech, a clause introduced by když is usually followed by a comma when the main clause comes after it:

• Když má můj syn hlad, ...

That comma is standard and important.

In Czech, mít hlad literally means to have hunger, and it is the normal everyday way to say to be hungry.

So:

• mám hlad = I am hungry
• má hlad = he is hungry

You can say je hladový too, but that sounds more descriptive, like he is hungry/hungry-looking. In ordinary conversation, má hlad is much more common.

Můj syn is in the nominative because it is the subject of the clause:

• můj syn = my son

Here, syn is masculine animate singular, and můj agrees with it:

• nominative masculine singular: můj

Since my son is the one who has hunger, nominative is required.

Měla by means should or ought to.

It is built from:

• měla = feminine singular past form of mít
• by = a particle used to form the conditional

Together:

• měla by dát = she should give

This is how Czech commonly expresses should:

• měl by = he should
• měla by = she should
• měli by = they should

Even though měla looks like a past form, měla by does not mean past here. It is a conditional construction used for advice, recommendation, or mild obligation.

Both are possible.

• měla by mu maminka dát...
• maminka by mu měla dát...

Czech word order is flexible, so the difference is mostly about emphasis and style.

The sentence you have is perfectly natural. Starting with měla by puts the modal idea should a bit earlier. Using maminka by měla would place more focus on maminka.

Maminka means mom/mummy/mommy, while matka means mother.

• maminka sounds warmer, more personal, and more natural in everyday family speech
• matka is more formal, neutral, or sometimes even a bit stiff in ordinary conversation

So in a sentence about feeding a child, maminka sounds very natural.

Mu means to him.

It is the dative form of the pronoun on (he):

• on = he
• mu = to him

In the sentence:

• měla by mu maminka dát banán nebo pomeranč
• literally: mom should give him a banana or an orange

The person receiving the thing given is in the dative in Czech.

Czech word order is much freer than English word order. Short pronouns like mu often come early in the clause, usually in the so-called second position area.

So mu naturally appears near the beginning of the main clause:

• měla by mu maminka dát...

Other orders are possible too, for example:

• maminka by mu měla dát...
• maminka mu má dát... (different nuance)
• měla by maminka mu dát... (less natural)

The version in your sentence sounds natural because:

• měla by forms the modal structure
• mu comes early as a short clitic pronoun
• maminka follows
• dát stays at the end

Dát is the perfective verb, while dávat is the imperfective verb.

Here, the sentence is about giving one specific item:

• a banana
• or an orange

That is a single completed action, so dát is the natural choice.

Compare:

• Měla by mu dát banán. = She should give him a banana.
• Dává mu ovoce každý den. = She gives him fruit every day.

Use dát for one completed giving event; use dávat for repeated or ongoing giving.

They are in the accusative singular, because they are the direct objects of dát.

For masculine inanimate nouns like these, the accusative singular is the same as the nominative singular:

• banán → banán
• pomeranč → pomeranč

So although they are objects, their forms do not visibly change here.

Czech, like English, can simply join two alternatives with nebo = or.

So:

• dát banán nebo pomeranč = give a banana or an orange

There is no need to repeat dát or mu.

Usually nebo just means ordinary or, and the exact meaning depends on context.

In this sentence, most people would understand it as choosing one of the two:

• a banana
• or an orange

If the speaker wanted to emphasize one or the other, but not both, context or intonation would usually do that. Czech does not normally need a special separate form here.

Czech has no articles like a, an, or the.

So:

• banán can mean a banana or the banana
• pomeranč can mean an orange or the orange

The exact meaning comes from context. In your sentence, English naturally uses a banana or an orange, but Czech simply uses the noun without an article.

Yes, Czech often omits subjects when they are clear from the verb form.

You could say:

• Když má můj syn hlad, měla by mu dát banán nebo pomeranč.

That still works, because měla by dát already suggests a feminine singular subject, and the context may make it clear who she is.

However, including maminka makes the sentence more explicit.

Because once my son has already been introduced, Czech naturally switches to a pronoun.

So:

• můj syn = my son
• mu = to him

Repeating the full noun phrase would be possible, but less natural:

• Když má můj syn hlad, měla by maminka dát synovi banán nebo pomeranč.

That is grammatically correct, but the version with mu sounds smoother and more natural.

Yes.

• měla by mu maminka dát...
• měla by maminka synovi dát...

Both are correct.

Mu is shorter and more natural when the referent is already known.
Synovi is more explicit and may be used for emphasis or clarity.

It sounds more like a general recommendation or habitual situation:

• When my son is hungry, mom should give him a banana or an orange.

That general meaning comes from:

• když = when
• má hlad = is hungry
• měla by = should

So it sounds like advice or a usual response, not just one single event.

In some contexts, English might translate když almost like if, especially in general statements. But the basic Czech meaning here is still when.

So:

• Když má můj syn hlad...
  means roughly When my son is hungry...

In real use, this can overlap with the idea If my son is hungry..., but Czech normally uses když for this kind of real, expected situation.

A rough English-friendly approximation is:

• Když má můj sin hlad, mňela bi mu maminka daht banahn nebo pomeranch.

A few useful notes:

• když: the ž sounds like the s in measure
• můj: the ůj is a diphthong, something like oo-y
• měla: the mě sounds roughly like m-nye
• dát: long á
• pomeranč: final č sounds like ch in church

This is only approximate, but it can help at first.