Jedno století je dlouhá doba.

Because století is a neuter noun.

In Czech, one changes form to match the gender of the noun:

• jeden = masculine
• jedna = feminine
• jedno = neuter

So:

• jeden rok = one year
• jedna doba = one period
• jedno století = one century

Since století is neuter, jedno is the correct form.

A good clue is the ending -í. Many Czech nouns ending in -í are neuter, including:

• náměstí = square
• nádraží = station
• poschodí = floor/story
• století = century

Also, adjectives and numerals around the noun confirm it. Here, jedno shows that století is neuter.

Století means century.

It is historically connected to:

• sto = hundred
• let = years

So the idea is basically a hundred-year period.

You may also notice that Czech sometimes expresses this idea more literally as sto let = a hundred years.

Because doba is a feminine noun, and the adjective must agree with it.

The adjective dlouhý = long changes by gender:

• dlouhý = masculine
• dlouhá = feminine
• dlouhé = neuter

Since doba is feminine, you say dlouhá doba.

Everything is in the nominative singular.

• Jedno století is the subject.
• je means is.
• dlouhá doba is the predicate noun phrase after to be, and in Czech this is commonly also in the nominative.

So:

• jedno = nominative neuter singular
• století = nominative neuter singular
• dlouhá = nominative feminine singular
• doba = nominative feminine singular

Czech does not have articles like English a/an/the.

That means a noun can often stand alone:

• století can mean a century or the century, depending on context.

Here, jedno literally means one, but it can also help express the idea of one single century. In some contexts, English a century may be translated simply as století, and in others as jedno století, depending on the intended emphasis.

It primarily means one, but in some sentences it can sound close to one single or can help make the noun feel more specific as a single unit.

So Jedno století je dlouhá doba is very natural as:

• One century is a long time
• and in some contexts, effectively A century is a long time

If you remove jedno, you get Století je dlouhá doba, which is also possible, but it feels a bit more general or less explicitly countable.

Because doba usually means a period, span, or length of time, while čas often means time in a broader sense.

Compare:

• dlouhá doba = a long period / a long time
• čas = time in general, clock time, or time as a concept

In this sentence, Czech prefers doba because a century is a time span, not just time in the abstract.

Je is the 3rd person singular form of být, which means to be.

So:

• jsem = I am
• jsi/jseš = you are
• je = he/she/it is

In this sentence, je means is.

Yes. Czech word order is more flexible than English.

The basic sentence is:

• Jedno století je dlouhá doba.

But you might also hear:

• Dlouhá doba je jedno století.
  This is grammatically possible, but less natural in normal conversation unless you are emphasizing long time.

Most naturally, the original order presents:

1. the topic: Jedno století
2. the comment about it: je dlouhá doba

So the given sentence is the most neutral and natural version.

A simple pronunciation guide is:

YED-no STO-le-tee ye DLOU-haa DO-ba

A few helpful points:

• j is pronounced like English y
• ou in dlouhá is a real diphthong, roughly like oh-oo said smoothly together
• í and á are long vowels, so hold them a bit longer:
  • století
  • dlouhá

Stress in Czech is normally on the first syllable of each word:

• JED-no
• STO-le-tí
• JE
• DLOU-há
• DO-ba

Yes, absolutely.

• sto let = a hundred years
• století = a century

So these are very close in meaning:

• Jedno století je dlouhá doba.
• Sto let je dlouhá doba.

The first uses the single noun century; the second uses the more literal phrase a hundred years. Both are natural.

Because in this sentence it is in the nominative singular, which is its basic dictionary form.

Also, some neuter nouns ending in -í keep that ending in several forms, so they may not seem to change as much as other nouns. That can feel unusual to English speakers, but it is normal in Czech.

Yes. It is complete, grammatical, and natural.

It has:

• a subject: Jedno století
• a verb: je
• a predicate complement: dlouhá doba

So it works perfectly as a full statement: One century is a long time.