Kód je jedno slovo.

Because slovo is a neuter noun in Czech.

The number one changes form to match the gender of the noun:

• jeden for masculine
• jedna for feminine
• jedno for neuter

So:

• jeden muž = one man
• jedna žena = one woman
• jedno slovo = one word

Since slovo is neuter, jedno is the correct form.

Both kód and jedno slovo are in the nominative here.

• kód is the subject
• jedno slovo is the predicate noun after je (is)

In a simple identification sentence like this, Czech commonly uses the nominative:

• Kód je heslo.
• To je dům.
• Kód je jedno slovo.

So this is a very straightforward nominative structure.

Je is the 3rd person singular form of the verb být (to be).

The subject is kód = code, which is singular, so Czech uses:

• je = is

Examples:

• Kód je krátký. = The code is short.
• Dům je velký. = The house is big.

So Kód je jedno slovo. literally follows the pattern:

• code + is + one word

It can mean either, depending on context.

Czech has no articles like a/an and the, so kód by itself can mean:

• a code
• the code

The exact meaning comes from the situation. In many real contexts, English would translate it as the code if both speaker and listener already know which code is being discussed.

Yes. Jedno slovo can naturally be understood as:

• one word
• a single word

So the sentence can imply that the code is made up of only one word, not several words.

The basic word order here is very natural:

• Kód je jedno slovo.

But Czech word order is more flexible than English. You could change it for emphasis, for example:

• Jedno slovo je kód. — grammatically possible, but marked and less natural in most contexts
• Kód je jen jedno slovo. — The code is only one word

In normal neutral speech, Kód je jedno slovo. is the best choice.

A rough pronunciation guide for an English speaker is:

• Kód ≈ kohd
• je ≈ ye
• jedno ≈ yed-no
• slovo ≈ slo-vo

A few useful notes:

• ó is a long vowel, so kód has a longer o
• j in Czech is pronounced like English y in yes
• Stress in Czech is usually on the first syllable of each word:
  • KÓD
  • JE
  • JED-no
  • SLO-vo

The accent mark in kód shows that the vowel is long.

So:

• o = short o
• ó = long o

In Czech, vowel length can matter, so it is important to write and pronounce it correctly.

Yes. Ten kód je jedno slovo is also correct.

Ten means that or sometimes works a bit like the when you want to point out a specific noun more clearly.

Compare:

• Kód je jedno slovo. = The code / a code is one word.
• Ten kód je jedno slovo. = That code / the code is one word.

The version without ten is more neutral and general.

The plural of slovo is slova.

So if you wanted to say The code is two words, you would say:

• Kód jsou dvě slova.

Notice two changes:

• je becomes jsou because dvě slova is plural
• dvě is the form of two used with neuter nouns like slova

So singular:

• Kód je jedno slovo.

Plural:

• Kód jsou dvě slova.