Když ti nechutná kyselý jogurt, můžeš si do něj dát sladké jahody.

In Czech, když can mean both when and if, depending on context.

Here it introduces a condition:

Když ti nechutná kyselý jogurt...
= If you don't like sour yogurt...

This is very common in everyday Czech. More formal alternatives for if are jestli or pokud, but když is natural and common in speech.

The verb chutnat works differently from English to like.

It literally means something like:

• to taste good to someone
• to be pleasing in taste to someone

So in Czech, the thing is the grammatical subject, and the person goes in the dative:

• Jogurt ti chutná. = You like the yogurt.
• literally: The yogurt tastes good to you.

So:

• kyselý jogurt = the subject
• ti = to you
• nechutná = does not taste good

That is why Czech uses ti nechutná here instead of a structure closer to English you don't like.

Ti is the short dative form of ty (you, singular informal).

Here it means to you:

• ti nechutná = doesn't taste good to you

Compare:

• ti = short, unstressed form
• tobě = full/emphatic form

So:

• Když ti nechutná... = neutral, normal
• Když tobě nechutná... = more emphatic, like if you don't like it

It is in the nominative because it is the subject of nechutná.

With chutnat, Czech treats the thing being liked as the subject:

• Kyselý jogurt ti nechutná.
• literally: Sour yogurt doesn't taste good to you.

So:

• kyselý jogurt = nominative singular
• ti = dative
• nechutná = 3rd person singular

This feels unusual to English speakers because English says you don't like yogurt, where you is the subject.

Si is the short reflexive dative form. In this sentence, it gives the meaning for yourself.

The expression dát si is very common and often means:

• to have
• to take
• to eat/drink
• sometimes to add for oneself

So:

• můžeš si dát sladké jahody = you can add/have/put in some sweet strawberries

Here si makes the action sound natural and personal: you are doing it for your own benefit, to your own yogurt.

Yes, dát often means to give, but it has several common uses.

One very common pattern is:

• dát něco do něčeho = to put something into something

So here:

• dát si do něj sladké jahody = to put/add sweet strawberries into it

In natural English, add is the best translation, but the Czech verb is still dát.

Also, dát is perfective, so it fits well with a single completed action: adding the strawberries.

Because the verb phrase is:

• dát něco do něčeho = put something into something

The preposition do always takes the genitive.

So:

• do jogurtu = into the yogurt
• do něj = into it

Here něj refers back to jogurt.

A useful thing to remember is that Czech personal pronouns often change form after prepositions. You do not say just do on or something similar; you need the correct prepositional/genitive form:

• on / ono → něj

Because jahody is plural, and the adjective has to agree with it.

• jahoda = strawberry
• jahody = strawberries

Here jahody is the direct object of dát, so it is in the accusative plural. For this noun, the accusative plural looks the same as the nominative plural:

• sladké jahody

So the adjective sladké matches jahody in:

• gender: feminine
• number: plural
• case: accusative

Because ti and si are short unstressed clitic forms, and Czech usually places clitics near the beginning of the clause, often in the second position.

So:

• Když ti nechutná kyselý jogurt...
• můžeš si do něj dát sladké jahody

This is very normal Czech word order.

English speakers often want to place these words later, but Czech strongly prefers these short pronouns early in the clause.

Yes, literally it means sour yogurt.

Depending on context, it may refer to yogurt that tastes tart or plain/unsweetened yogurt. Czech often uses kyselý for things with a sour or tangy taste.

So in this sentence, the contrast is:

• kyselý jogurt = sour/tart yogurt
• sladké jahody = sweet strawberries

That contrast helps the sentence make sense: if the yogurt is too sour for you, add something sweet.

Yes, you could. That would also mean if you don't like sour yogurt...

But there is a slight style difference:

• když = very common, natural, conversational
• jestli = also common, often clearly conditional or meaning whether/if
• pokud = more formal, more like provided that / if

So in everyday Czech, když sounds completely natural here.