Začátek byl tichý, ale konec byl skvělý.

They are both in the nominative singular.

That is because they are the subjects of the sentence:

• začátek = the beginning
• konec = the end

So in Začátek byl tichý, ale konec byl skvělý, both nouns are simply the things being described.

Byl is the past tense of být = to be.

More specifically, byl is the form used with a masculine singular subject. Since both začátek and konec are masculine singular nouns, byl matches them.

Compare:

• byl = masculine singular
• byla = feminine singular
• bylo = neuter singular

So:

• Začátek byl tichý.
• Kniha byla zajímavá.
• Město bylo krásné.

Because they are adjectives agreeing with masculine singular nouns.

In Czech, adjectives must agree with the noun they describe in:

• gender
• number
• case

Here:

• začátek is masculine singular nominative
• konec is masculine singular nominative

So the adjectives also appear in the masculine singular nominative form:

• tichý
• skvělý

Because with být + adjective, Czech normally uses the nominative for the adjective.

So:

• Začátek byl tichý.
• Konec byl skvělý.

This is different from some other structures where Czech may use other cases, but with a simple predicate adjective like this, nominative is the normal choice.

Yes, Czech can leave out the second byl if the meaning is clear.

So both of these are possible:

• Začátek byl tichý, ale konec byl skvělý.
• Začátek byl tichý, ale konec skvělý.

The version with byl repeated sounds a bit more balanced and explicit. Repeating it is completely natural.

Because Czech does not have articles like the or a/an.

So:

• začátek can mean beginning or the beginning
• konec can mean end or the end

You understand the exact meaning from the context, not from an article.

Ale means but.

The comma is standard in Czech before coordinating conjunctions like ale when they connect two clauses or contrasting parts.

So:

• Začátek byl tichý, ale konec byl skvělý.
• The beginning was quiet, but the end was great.

The comma here is normal and expected.

They are both masculine inanimate nouns.

That matters because it affects:

• the past tense form: byl
• the adjective endings: tichý, skvělý

If the subject had a different gender, the sentence would change. For example:

• Píseň byla tichá.
• Představení bylo skvělé.

So gender is an important part of Czech grammar, even for nouns that refer to abstract things like beginning or end.

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

The neutral order here is:

• Začátek byl tichý, ale konec byl skvělý.

But Czech can move things around for emphasis. For example, you might hear:

• Tichý byl začátek, ale skvělý byl konec.

That sounds more marked or stylistic. For a learner, the original version is the safest and most natural basic pattern.

A rough pronunciation guide is:

• Začátek ≈ zah-CHAA-tek
• byl ≈ bil
• tichý ≈ TI-khee
• ale ≈ AH-le
• konec ≈ KO-nets
• skvělý ≈ SKVYE-lee

A few useful sound notes:

• č sounds like ch in church
• ch sounds like the ch in Scottish loch or German Bach
• c sounds like ts
• ě often makes the previous consonant softer and is heard roughly like ye in this word: skvělý

Also, Czech stress is usually on the first syllable of each word:

• ZAčátek
• TIchý
• KOnec
• SKVĚlý

Yes. Tichý can mean:

• quiet
• silent
• subdued
• calm in sound

So in context, Začátek byl tichý could suggest that the beginning was not loud, not dramatic, or rather subdued.

Likewise, skvělý means something like:

• great
• excellent
• wonderful

So the contrast is between a quiet/subdued start and a very good ending.