Můžeš mi prosím napsat svoji adresu na tu obálku?

Můžeš is the 2nd person singular present form of the verb moci, meaning can / be able to.

So:

• moci = to be able to, can
• můžeš = you can

In this sentence, Czech uses Můžeš ...? the same way English uses Can you ...? to make a request.

The ending -š tells you the subject is you singular, so Czech does not need to say ty explicitly.

Czech often leaves out subject pronouns when they are already clear from the verb ending.

Here, Můžeš already means you can, so adding ty is unnecessary.

• Můžeš mi prosím napsat... = normal, natural
• Ty mi můžeš prosím napsat... = possible, but usually adds emphasis or contrast

This is very common in Czech.

Mi means to me or for me. It is the short dative form of já.

So:

• mi = to me / for me

In this sentence, it shows who wants the action done:

• Můžeš mi prosím napsat... = Can you write ... for me / to me, please?

Czech often uses these short pronoun forms in requests.

Because mi is a clitic, a short unstressed word that usually goes in second position in the sentence.

So Czech prefers:

• Můžeš mi prosím napsat svoji adresu...

rather than placing mi later.

This second-position behavior is very typical for short pronouns like:

• mi, ti, mu
• se, si
• ho, ji, je

English speakers often need time to get used to this.

Prosím means please.

It makes the request softer and more polite:

• Můžeš mi napsat... = Can you write...
• Můžeš mi prosím napsat... = Can you please write...

Its position is somewhat flexible, but this placement is very natural.

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

• psát = imperfective = to write, to be writing, to write in general
• napsat = perfective = to write down, to write completely, to finish writing

In this sentence, the speaker wants a completed result: the address written on the envelope. That is why napsat is used.

So:

• Můžeš mi napsat svoji adresu...? = Can you write your address...?
• using psát here would sound less natural for this one completed action

Svoji is a form of the reflexive possessive pronoun svůj, which means one’s own.

Czech normally uses svůj when the possessor is the same as the subject.

Here the subject is the person being asked, understood as you, and the address also belongs to that same person. So Czech naturally says:

• svoji adresu = your own address

Using tvou adresu is not impossible, but svoji is usually preferred in this kind of sentence because it clearly shows the address belongs to the person doing the writing.

In this sentence, yes, basically.

For feminine accusative singular, Czech often allows both:

• svou adresu
• svoji adresu

Both are used and understood. Svou is often taught first and may sound a bit more neutral or formal in some contexts, while svoji is also very common in everyday speech and writing.

So if you have learned svou adresu, that is perfectly fine too.

Because adresu is the accusative singular form of adresa.

• adresa = nominative, the basic dictionary form
• adresu = accusative singular

It is accusative because it is the direct object of napsat:

• write what?
• adresu

That is why the ending changes.

Na tu obálku means onto that envelope / on that envelope.

Here:

• na = on, onto
• tu = accusative form of ta = that
• obálku = accusative singular of obálka = envelope

Czech uses na + accusative when there is movement or placing onto a surface, or when something is being put/written onto it.

Because the address is being written onto the envelope, na tu obálku is natural.

Yes, na can take either accusative or locative, depending on meaning.

A very useful rule is:

• na + accusative = movement toward a surface / placing onto it
• na + locative = location on a surface

So compare:

• Napsat adresu na tu obálku = write the address onto that envelope
• Adresa je na té obálce = the address is on that envelope

In your sentence, the action results in the writing being put onto the envelope, so accusative is used.

The word order is somewhat flexible, but not completely free.

The given sentence is very natural:

• Můžeš mi prosím napsat svoji adresu na tu obálku?

Possible variations can shift emphasis, but some rules still matter, especially the early placement of clitics like mi.

For example:

• Můžeš mi napsat svoji adresu na tu obálku, prosím? = also possible
• Prosím, můžeš mi napsat svoji adresu na tu obálku? = also natural

But moving everything around randomly can sound awkward. Czech word order often reflects information structure and emphasis more than English does.

It is polite, but informal.

Why?

• prosím makes it polite
• můžeš is the informal singular form, used with ty

So this is something you would say to:

• a friend
• a classmate
• a family member
• someone you address with ty

If you want the formal version, you would normally say:

• Můžete mi prosím napsat svoji adresu na tu obálku?

That uses můžete, the formal or plural form.