Řekni mi prosím, kde je pošta.

Řekni is the imperative form of říct / říkat, meaning tell or say.
So Řekni mi... means Tell me...

This is the singular informal command, used when speaking to one person you address as ty.

Examples:

• Řekni mi to. = Tell me that.
• Počkej! = Wait!

If you wanted to be more polite or address more than one person, you would usually say:

• Řekněte mi prosím... = Please tell me...

Mi is the dative form of já and means to me.

In Czech, with verbs like říct / říkat (to tell / say), the person receiving the information is usually in the dative:

• Řekni mi... = Tell me
• Řeknu ti... = I’ll tell you

Mě is usually accusative or genitive, not the form needed here.

Compare:

• Vidíš mě? = Do you see me? → accusative
• Řekni mi pravdu. = Tell me the truth. → dative

Prosím means please here. It makes the request softer and more polite.

Without it:

• Řekni mi, kde je pošta. = Tell me where the post office is.

With it:

• Řekni mi prosím, kde je pošta. = Please tell me where the post office is.

A useful thing to know is that prosím can also mean:

• you’re welcome
• go ahead
• pardon?

So it is a very common multifunctional word in Czech.

Czech word order is more flexible than English, but some orders sound more natural than others.

Řekni mi prosím, kde je pošta. is a normal, natural order:

• Řekni = Tell
• mi = me
• prosím = please

You may also hear:

• Prosím, řekni mi, kde je pošta.
• Řekni mi, prosím, kde je pošta.

These all mean basically the same thing. The choice often depends on rhythm, emphasis, or style.

Both are possible in Czech, but kde je pošta is the most neutral and natural order.

This part means where the post office is:

• kde = where
• je = is
• pošta = post office / post

Czech often places the verb early in simple neutral sentences:

• Kde je pošta? = Where is the post office?

You can say kde pošta je, but it usually sounds more marked or emphatic.

It can mean more than one thing depending on context.

Pošta may mean:

• post office (the building or institution)
• mail / post

In this sentence, because of kde je... (where is...), it clearly means the post office.

Examples:

• Kde je pošta? = Where is the post office?
• Přišla pošta. = The mail arrived.

The comma separates the main clause from the subordinate clause.

Main clause:

• Řekni mi prosím = Please tell me

Subordinate clause:

• kde je pošta = where the post office is

Czech punctuation usually requires a comma before clauses introduced by words like:

• kde = where
• že = that
• když = when
• protože = because

So the comma here is standard Czech punctuation.

The Czech letter ř is famous because it is difficult for many learners. It is a special Czech sound, something like a mix of r and zh.

A rough guide:

• Start with a rolled or tapped r
• Add a zh sound, like the s in measure

It does not exist in standard English.

If that sound is still hard, many learners begin with a simpler r-like sound and improve over time. Native speakers are used to foreigners struggling with ř.

Je means is. It is the 3rd person singular form of být (to be).

So:

• je = is

Examples:

• To je dobré. = That is good.
• Kde je stanice? = Where is the station?
• Pošta je tamhle. = The post office is over there.

It is understandable, but to a native speaker it may sound a little unusual if you are talking to a stranger, because řekni is informal singular.

To one friend, it is fine:

• Řekni mi prosím, kde je pošta.

To a stranger, a more natural polite version would be:

• Řekněte mi prosím, kde je pošta. or even more naturally:
• Prosím vás, kde je pošta?
• Nevíte prosím, kde je pošta? = Do you happen to know where the post office is?

So the sentence is grammatically fine, but the best choice depends on who you are speaking to.

Yes. Kde je pošta? is the simplest direct question: Where is the post office?

The full sentence:

• Řekni mi prosím, kde je pošta.

is more like:

• Please tell me where the post office is.

So the shorter version is often more natural if you are simply asking for directions.

Most directly, řekni is the imperative of říct, which is usually perfective and often means say / tell once.

Related pair:

• říkat = to say, to be saying, to tell repeatedly / habitually
• říct = to say / tell (single completed act)

So:

• Řekni mi... = Tell me...
• Říkej mi... would sound different and is not the normal choice here

For a simple request for information, řekni is exactly what you would expect.