Můžete si vybrat jakýkoli den.

Můžete means you can or you may.

It is the 2nd person plural form of moci = to be able / can. In Czech, this form is used for:

• you all can
• you can when speaking politely to one person

So this sentence can address either several people or one person formally.

Because moci is an irregular verb.

Its present-tense forms are built from the stem můž-, not from moc-:

• můžu / mohu = I can
• můžeš = you can
• může = he/she/it can
• můžeme = we can
• můžete = you can
• můžou / mohou = they can

So moci → můžete is something you mostly just have to learn as part of the verb’s conjugation.

Because after a modal verb like moci (can), Czech normally uses the infinitive of the main verb.

So:

• Můžete = you can
• vybrat = choose

Together: Můžete vybrat = You can choose

This works just like English can choose.

si is a reflexive dative pronoun, but in this sentence the most useful thing to know is that vybrat si is the normal expression for to choose / to pick.

So you should learn:

• vybrat si = to choose, to pick out

Very often, si is not translated separately into English. It does not mean that the English sentence needs a word like self.

You can think of vybrat si as a set expression.

Because in everyday Czech, vybrat si is the usual way to say choose/select something for oneself.

Without si, vybrat can have a broader range of meanings depending on context, such as pick out, take out, collect, or select. But when talking about choosing an option, vybrat si is very common and natural.

So Můžete si vybrat... sounds more idiomatic than just Můžete vybrat... in this context.

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

• vybrat = perfective
  focuses on completing the choice
• vybírat = imperfective
  focuses on the process, repetition, or ongoing action of choosing

In Můžete si vybrat jakýkoli den, the idea is that you are allowed to make a choice, so the perfective verb vybrat is natural.

A rough contrast:

• Můžete si vybrat jakýkoli den. = You can choose any day.
• Můžete si vybírat. = You can keep choosing / browse / take your time choosing.

jakýkoli means any, whatever, or any kind of depending on context.

Here jakýkoli den means any day or whichever day you want.

It is written as one word.

You may also see the variant jakýkoliv, which means the same thing.

Yes, very often you could, and in many contexts both sound natural.

A useful rough distinction is:

• jakýkoli = any ... whatsoever
• kterýkoli = any one of a set

So:

• jakýkoli den suggests no real restriction: any day at all
• kterýkoli den can sound like any one of the available days

In normal conversation, though, the difference is often small, and both may be acceptable.

Because den is the direct object of vybrat si, so it is in the accusative singular.

The important thing is that den is masculine inanimate, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: den
• accusative: den

That is why the form does not visibly change here.

Because jakýkoli has to agree with den in:

• gender: masculine
• number: singular
• case: accusative

Since den is masculine inanimate singular accusative, jakýkoli also takes the matching form jakýkoli.

In this pattern, the accusative looks the same as the nominative, so nothing changes visibly.

For comparison:

• jakýkoli den = any day
• jakoukoli noc = any night

The second example changes more clearly because noc is feminine.

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

The sentence Můžete si vybrat jakýkoli den is a very natural neutral version.

But you could also say:

• Jakýkoli den si můžete vybrat.

That version puts more emphasis on jakýkoli den.

One important detail: si is a clitic, so it usually comes near the beginning of the sentence, often in second position.

That is why Czech tends to place si early:

• Můžete si vybrat...
• Jakýkoli den si můžete vybrat.

You would say:

Můžeš si vybrat jakýkoli den.

Compare:

• Můžeš si vybrat jakýkoli den. = informal singular
• Můžete si vybrat jakýkoli den. = formal singular or plural

So the only change is můžeš instead of můžete.

A simple English-friendly approximation is:

MOO-zhe-te si VIH-brat YA-kee-ko-li den

A few pronunciation notes:

• ů in Můžete is a long oo sound
• ž sounds like the s in measure
• y / ý is not pronounced like English y; here ý is a long vowel
• r in vybrat is a rolled or tapped Czech r

A more careful pronunciation guide would be roughly:

[MOO-zhe-te si VIH-brat YAH-kee-ko-li den]

It can express either, depending on context.

Můžete can mean:

• you can = ability/possibility
• you may = permission

In this sentence, the most likely meaning is permission/allowed choice:

You may choose any day.

But in another context it could also sound like it is possible for you to choose any day. Czech often leaves that distinction to the situation rather than marking it explicitly.