Přijdu přesně v deset.

Because přijdu comes from the perfective verb přijít. In Czech, perfective verbs do not normally have a true present meaning. Their present-form endings are used to express the future.

So:

• přijít = to come / to arrive (perfective)
• přijdu = I will come / I will arrive

If you wanted an ongoing or habitual meaning, Czech would use the imperfective verb přicházet instead.

Přijdu is:

• 1st person singular
• from přijít
• perfective
• future in meaning

So it literally means I will come or I will arrive.

The ending -u tells you the subject is I, which is why Czech does not need the pronoun já here.

Czech often drops subject pronouns when they are clear from the verb form.

Here, přijdu already tells you the subject is I. So já is unnecessary unless you want emphasis or contrast:

• Přijdu přesně v deset. = neutral
• Já přijdu přesně v deset. = I will come exactly at ten (maybe contrasting with someone else)

This is very normal in Czech.

It can mean either, depending on context.

In a sentence about time, English often prefers arrive:

• Přijdu přesně v deset. = I’ll arrive exactly at ten.

But I’ll come exactly at ten is also possible if the context is about coming to a place or event.

So the Czech verb přijít often covers both ideas.

Přesně means exactly, precisely, or sometimes right in the sense of exact timing.

So:

• přesně v deset = exactly at ten
• right at ten

It emphasizes that the speaker means the time very precisely, not approximately.

V deset means at ten.

With clock times, Czech commonly uses v:

• v jednu = at one
• ve dvě = at two
• v deset = at ten

So in this sentence, v is the normal preposition for a specific clock time.

No. V deset is completely natural and very common.

You can also say:

• v deset hodin

That is a bit more explicit, and sometimes slightly more formal or careful, but in everyday speech v deset is enough.

So both are correct:

• Přijdu přesně v deset.
• Přijdu přesně v deset hodin.

Czech sometimes changes v to ve for easier pronunciation, especially before certain consonant combinations.

For example:

• ve dvě
• ve škole
• ve středu

But before deset, normal Czech uses v:

• v deset

So ve deset would not be standard here.

In time expressions like this, Czech uses the form found in expressions such as:

• v jednu
• ve dvě
• v pět
• v deset

With deset, the visible form is just deset, so there is no obvious change for the learner to notice. The important practical point is simply this: v deset is the correct fixed time expression meaning at ten.

For beginners, it is best to learn v deset as a whole phrase.

Yes, but the emphasis changes.

The neutral version is:

• Přijdu přesně v deset.

You could also say:

• Přesně v deset přijdu. = stronger emphasis on the exact time
• Přijdu v deset přesně. = also possible, with přesně sounding a little more like an afterthought or reinforcement

Czech word order is flexible, but the original sentence is a very natural neutral choice.

Roughly:

• PŘIJdu PŘESně v DEset

A few useful points:

• Czech stress is usually on the first syllable of each word.
• ř is a special Czech sound that English speakers often find difficult.
• přijdu is pronounced as one word, not like separate pieces.

A rough learner-friendly approximation might be:

• PRZHIY-doo PŘES-nye v DEH-set

But the biggest challenge is the sound ř, which does not exist in English.