Síla je důležitá.

A natural pronunciation is approximately:

SEE-lah yeh DOO-zheh-lee-tah

A few helpful points:

• Síla:
  
  • Sí has a long í, so hold it a bit longer: see
  • la is like lah
• je is pronounced yeh
• důležitá:
  • dů sounds roughly like doo
  • ž sounds like the s in measure
  • the stress in Czech is normally on the first syllable of the word, so DŮležitá

So even though some vowels are long, Czech word stress usually stays on the first syllable.

Because it agrees with síla, which is a feminine singular noun.

In Czech, adjectives must match the noun they describe in:

• gender
• number
• case

Here:

• síla = feminine singular
• so důležitý changes to důležitá

This is the feminine singular nominative form.

A few comparison examples:

• důležitý muž = an important man
• důležitá síla = an important force/strength
• důležité město = an important city

Yes, síla is feminine.

A very common clue in Czech is that many nouns ending in -a are feminine. That is not true in every single case, but it is a very useful pattern.

So:

• síla → feminine
• therefore the adjective becomes důležitá

As you learn Czech, it is good to memorize nouns together with their gender, because that affects adjectives, pronouns, and sometimes verb forms in the past tense.

It is in the nominative singular.

Why? Because síla is the subject of the sentence:

• Síla = the thing being talked about
• je důležitá = is important

In simple X is Y sentences, the subject is usually in the nominative.

So here:

• síla = nominative singular
• důležitá also appears in nominative singular feminine to match it

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

So:

• jsem = I am
• jsi / jste = you are
• je = he/she/it is
• jsme = we are
• jsou = they are

In Síla je důležitá, je means is.

Unlike in some languages, Czech usually keeps the verb to be in this kind of present-tense sentence, so you do not normally drop it here.

Yes, you can, but the emphasis changes.

Czech word order is more flexible than English word order because endings carry a lot of grammatical information.

Compare:

• Síla je důležitá. → neutral statement
• Důležitá je síla. → puts more emphasis on important
• Síla je důležitá can sound like a plain fact
• Důležitá je síla can sound more contrastive, like What is important is strength

So the original sentence is the most neutral and standard version for a learner.

The accent marks mostly show vowel length.

In Czech, vowel length matters, so these are not just optional spelling marks.

• í = long i
• á = long a
• ů = long u

So in this sentence:

• síla has a long í
• důležitá has a long ů and a long final á

Czech distinguishes short and long vowels clearly, and changing vowel length can sometimes change the word.

Both represent a long u sound, but they are used in different spelling situations.

• ú is usually written at the beginning of a word or word part
• ů is usually written elsewhere

So in důležitá, the spelling uses ů because it is not at the beginning.

For pronunciation in modern Czech, they are basically the same vowel sound.

Ž is pronounced like the sound in English measure or vision.

So:

• ž ≈ zh

That means důležitá contains this sound in the middle:

• dů-le-ži-tá

This letter is very common in Czech, so it is worth getting used to early.

Not always. It depends on context.

Síla can mean things like:

• strength
• force
• power
• sometimes even intensity or effectiveness, depending on context

So in a sentence like Síla je důležitá, the exact English choice depends on what the wider topic is:

• physical ability → strength
• physics → force
• influence or energy → possibly power

That is normal in language learning: one Czech word often overlaps with several English words.

You should learn the dictionary form as důležitý.

In Czech, adjectives are usually listed in the masculine singular nominative form in dictionaries and vocabulary lists.

So:

• dictionary form: důležitý
• in this sentence: důležitá because it matches the feminine noun síla

This is a good habit:

• learn the noun with its gender
• learn the adjective in its dictionary form
• then practice how the adjective changes to agree with the noun

In standard Czech, no. You normally need je here.

So the standard sentence is:

• Síla je důležitá.

Leaving out je would sound ungrammatical in normal modern Czech prose and speech.

That is different from some other languages where to be can sometimes be omitted in the present tense. Czech usually keeps it in this kind of sentence.