To byla krádež.

Because in this kind of sentence, the past tense form of být often agrees with the noun that names what something was.

• krádež is a feminine noun
• so the verb is byla (feminine singular)

Compare:

• To byl problém. = That was a problem.
• To byla chyba. = That was a mistake.
• To bylo neštěstí. = That was a tragedy.

So even though to is neuter in form, the verb here follows krádež, which is feminine.

Here to means something like that or it, depending on context.

It is very common in Czech to use to in identifying sentences:

• To je můj bratr. = That is my brother.
• To byla krádež. = That was a theft.

So to is pointing to some situation, event, or thing already known from context.

Because grammatical gender in Czech is not determined only by the last letter.

Many feminine nouns do end in -a, but not all of them. Some feminine nouns end in a consonant, including words like:

• krádež = theft
• věc = thing
• noc = night

So you simply have to learn the gender along with the noun. In this sentence, you can also tell it is feminine because the verb is byla.

It is in the nominative.

In a sentence like To byla krádež, the noun names what something was, so nominative is normal.

This is similar to:

• To je problém.
• To byla nehoda.
• To byl omyl.

A learner may expect instrumental after být, because Czech often uses instrumental with roles or states, for example:

• Je učitelem. = He is a teacher.

But in this identifying pattern with to je / to byl / to byla / to bylo, nominative is the usual choice.

Yes, absolutely.

Both are possible:

• To byla krádež.
• Byla to krádež.

The difference is mainly one of word order and emphasis.

Very roughly:

• To byla krádež. puts more focus on to = that/this situation
• Byla to krádež. can sound a bit more neutral or matter-of-fact

Czech word order is flexible, so both are natural depending on context.

Because Czech has no articles.

So krádež can mean:

• a theft
• the theft
• sometimes just theft

The exact meaning depends on context, not on a separate article word.

That is why To byla krádež can be translated in different ways depending on the situation.

A simple pronunciation guide is:

to BI-la KRAA-desh

A few useful points:

• Czech stress is usually on the first syllable of each word
• byla sounds roughly like BI-la
• á is a long vowel
• ž sounds like the s in measure

So krádež is approximately KRAA-desh, though the final ž remains voiced in careful pronunciation.

Not exactly.

krádež means theft: taking something that is not yours.

loupež means robbery: theft involving force or threat.

So if someone secretly steals a wallet, that is krádež.
If someone threatens a person and takes money, that is loupež.

English sometimes uses robbery loosely, but Czech keeps this distinction more clearly.

Yes.

Czech to is broader than English it or that, and the best translation depends on context.

For example:

• if you are pointing back to an event: That was a theft
• if you are commenting on something already mentioned: It was theft

So the Czech sentence stays the same, while English may choose different wording.

Usually it refers to one specific situation.

For example, after hearing what happened, someone might say:

• To byla krádež. = That was theft.

It sounds like a judgment about a particular act or incident.

If you wanted to speak more generally about theft as a concept, Czech would normally use a different structure, not this sentence by itself.