Sekretářka mi později ukáže, v kolik hodin přijde šéf a kdy bude mít telefon novou baterii.

Mi means to me / for me here. It is the dative form of já.

The verb ukázat often works like ukázat komu co = show someone something. So:

• Sekretářka mi ukáže... = the secretary will show me ...
• mi = to me

By contrast, mě is mainly the accusative form, not the normal dative form in standard Czech. The full dative form is mně, and the short unstressed form is mi.

Because mi is a clitic: a short unstressed word that usually goes in the second position of the clause.

So in:

• Sekretářka mi později ukáže...

the first element is Sekretářka, and mi comes right after it.

If you changed the word order, the clitic would still normally stay in second position:

• Později mi sekretářka ukáže...

This is very typical Czech word order behavior and often feels unusual to English speakers at first.

Because everything after ukáže is a subordinate clause, more specifically an indirect question.

Czech normally separates subordinate clauses with a comma:

• Sekretářka mi později ukáže, v kolik hodin přijde šéf...

So the comma is not optional in standard writing.

Because this is not a that-clause. It is an indirect question.

Compare:

• Řekla, že přijde. = She said that she would come.
• Řekla, kdy přijde. = She said when she would come.

In your sentence, the secretary will show/tell the speaker:

• at what time the boss will arrive
• when the phone will have a new battery

So Czech uses the question words v kolik hodin and kdy, not že.

V kolik hodin asks for an exact clock time:

• V kolik hodin přijde šéf? = At what time will the boss arrive?

Kdy is broader and just means when:

• Kdy bude mít telefon novou baterii? = When will the phone have a new battery?

So:

• v kolik hodin = more specific, exact hour/time
• kdy = more general

You could sometimes use kdy for the boss too, but v kolik hodin makes it clearer that you want a precise time.

It is a fixed expression meaning at what time. Czech often uses:

• v kolik hodin = at what hour / at what time

So although English says at what time, Czech uses v kolik hodin. You should learn it as a set phrase.

A related question is:

• Kolik je hodin? = What time is it?

But when asking about the time of an event, Czech usually says:

• V kolik hodin...?

Because přijít is a perfective verb, and perfective verbs form the future with a simple present-looking form.

So:

• přijde = will arrive

Czech does not normally make the future of a perfective verb with bude + infinitive.

Compare:

• přijít → přijde = will arrive
• dělat → bude dělat = will do / will be doing

So bude přijít is not standard Czech.

Because mít is an imperfective verb, and imperfective verbs form the future with bude + infinitive.

So:

• bude mít = will have

That is the normal future form of mít.

This also shows a useful contrast in the same sentence:

• přijde = perfective future, one-word form
• bude mít = imperfective future, two-word form

Yes. Telefon is the subject.

The structure is:

• telefon = nominative subject
• bude mít = verb
• novou baterii = accusative object

So literally, Czech says:

• the phone will have a new battery

English might sometimes prefer something like the phone will get a new battery or there will be a new battery in the phone, but the Czech grammar here is straightforward: the phone is the thing that has the battery.

Because novou baterii is the direct object of mít, so it must be in the accusative case.

The base nominative form is:

• nová baterie = a new battery

But after mít, it changes to accusative:

• mít novou baterii = to have a new battery

Both words change as needed:

• nová → novou
• baterie → baterii

This is adjective-noun agreement in case, gender, and number.

It can be a bit broader than just physical show.

Ukázat often means:

• to show
• to point out
• to indicate
• to demonstrate

In this sentence, it may suggest that the secretary will show the information, perhaps on a screen, in a schedule, on paper, etc. If the idea were simply tell me, Czech might more naturally use řekne mi.

So ukáže is possible, but it has a slightly more concrete sense than plain tell.

It can be changed, but the emphasis changes, and the clitic mi still tends to stay in second position.

For example:

• Sekretářka mi později ukáže...
• Později mi sekretářka ukáže...

Both are possible, but they highlight different parts of the sentence.

Czech word order is much more flexible than English because case endings show the grammatical roles. Still, the order is not random: it often reflects topic, focus, and normal clitic placement.

Because Czech has no articles.

So Czech does not have direct equivalents of a and the in normal grammar. Whether something means a secretary, the secretary, a phone, or the phone depends on context.

That is why:

• Sekretářka
• šéf
• telefon

can all be understood definitely or indefinitely depending on the situation.