V lékárně čeká moje sestra, protože chce koupit lék pro naši babičku.

Because v means in or sometimes at, and when it describes location, it takes the locative case.

The base form is lékárna = pharmacy.
After v, it changes to lékárně:

• lékárna → base form
• v lékárně = in/at the pharmacy

A useful contrast:

• v lékárně = in/at the pharmacy
• do lékárny = to the pharmacy

So here, the sister is already there, which is why Czech uses v lékárně.

Czech word order is much more flexible than English word order.

Both of these are correct:

• V lékárně čeká moje sestra.
• Moje sestra čeká v lékárně.

The difference is mostly emphasis:

• V lékárně čeká moje sestra puts focus on where she is.
• Moje sestra čeká v lékárně is a more neutral subject-first order.

So the sentence starts with V lékárně because the speaker wants to foreground the location.

Yes, absolutely.

It means the same basic thing, but it sounds a bit more neutral and straightforward. Czech often changes word order to highlight different parts of the sentence rather than to change the core meaning.

So:

• V lékárně čeká moje sestra = emphasis on in the pharmacy
• Moje sestra čeká v lékárně = emphasis on my sister

Because Czech has no articles. It does not use words like a, an, or the.

So:

• lékárna can mean a pharmacy or the pharmacy
• lék can mean a medicine or the medicine
• sestra can mean a sister or the sister

The exact meaning depends on context.

That is why v lékárně čeká moje sestra can naturally mean My sister is waiting in the pharmacy even though there is no separate word for the.

Because protože means because and introduces a subordinate clause.

In Czech, subordinate clauses are normally separated by a comma. So:

• V lékárně čeká moje sestra, protože chce koupit lék...

This is standard Czech punctuation.

English also often uses a comma before because in some situations, but Czech is more systematic about separating clauses this way.

Because chtít = to want, and after it Czech commonly uses an infinitive to say what someone wants to do.

So:

• chce = she wants
• koupit = to buy

Together:

• chce koupit = she wants to buy

This works like English:

• I want to go
• She wants to buy
• They want to help

In Czech:

• chci jít
• chce koupit
• chtějí pomoci

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

• koupit is perfective
• kupovat is imperfective

Here, koupit is used because the sentence refers to one completed purchase: she wants to buy the medicine and finish that action.

So:

• chce koupit lék = she wants to buy a medicine / buy the medicine
• chce kupovat lék would sound unusual here, because it suggests an ongoing, repeated, or process-like action rather than one completed purchase

A simple way to think of it:

• koupit = buy successfully / as a complete action
• kupovat = be buying / buy repeatedly / buy in a general sense

Because pro means for in the sense of intended for, and pro takes the accusative case.

So:

• pro
  • accusative
• naše babička changes to naši babičku

This phrase means:

• for our grandmother

This is different from the dative, which is often used for to someone rather than for someone.

Compare:

• koupit lék pro naši babičku = to buy medicine for our grandmother
• dát lék naší babičce = to give medicine to our grandmother

Because both words have to match the case required by pro, which is the accusative.

The basic form is:

• naše babička = our grandmother

But after pro, it becomes accusative:

• pro naši babičku

What changes:

• naše → naši
• babička → babičku

This is a normal feminine singular accusative pattern.

So the sentence is a good example of agreement:

• the possessive word changes
• the noun changes
• both reflect the same case

Because Czech usually does not need subject pronouns when the verb form already shows the person and number.

For example:

• čeká = he/she/it waits
• chce = he/she/it wants

Since the sentence already has the subject moje sestra, adding ona would usually be unnecessary.

Czech uses pronouns like ona mainly for emphasis, contrast, or clarity.

For example:

• Ona chce koupit lék, ale on nechce.
  = She wants to buy the medicine, but he doesn’t.

Yes, má sestra is also correct.

Both mean my sister, but they differ a bit in style:

• moje sestra = more common in everyday neutral speech
• má sestra = shorter, sometimes a bit more formal, literary, or stylistically marked

English speakers often learn the short forms first:

• můj
• tvůj
• jeho
• etc.

But in real spoken Czech, the longer forms like moje, tvoje are very common.

So moje sestra is completely natural here.

Because lék is the normal Czech word for a medicine, a remedy, or a drug/medication in this kind of sentence.

• lék often refers to a specific medicine item
• léky = medicines, medication
• medicína usually means medicine as a field of science, not usually a pill or drug in everyday speech

So:

• koupit lék = buy a medicine / buy a remedy

That is the most natural choice here.

Czech often uses lék as a countable noun, where English may use medicine more generally as an uncountable word.

So Czech can naturally say:

• koupit lék = buy a medicine / buy some medicine

If the meaning is more general or plural, Czech could also use:

• koupit léky = buy medicines / medication

So the singular lék here suggests one specific medicine or remedy, but in translation English might still simply say medicine.

It can correspond to either one in English, depending on context.

Czech v lékárně literally means in the pharmacy, but in natural English, at the pharmacy is often just as good.

So both can work:

• My sister is waiting in the pharmacy
• My sister is waiting at the pharmacy

The Czech phrase itself does not force a strong distinction between those two English choices here.