Mowa jest jasna.

Mowa is a noun, not a verb. It most often means speech, spoken language, or way of speaking, depending on context.

So in this sentence, mowa is the thing being described as jasna.

It is different from:

• mówić = to speak
• mowa o... = it is about... / we are talking about... (a fixed expression)

Jest means is. It is the 3rd person singular form of być (to be).

So the structure is:

• mowa = subject
• jest = is
• jasna = adjective describing the subject

This is the normal way to say X is Y in Polish:

• Książka jest ciekawa. = The book is interesting.
• Herbata jest gorąca. = The tea is hot.

In normal standard Polish, Mowa jest jasna is the full and natural sentence.

You may sometimes see Mowa jasna in:

• headlines
• poetry
• slogans
• very compressed style

But for a learner, it is best to treat jest as required in ordinary sentences like this.

Because jasna has to agree with mowa.

Mowa is:

• feminine
• singular
• nominative

So the adjective must also be:

• feminine
• singular
• nominative

That gives jasna.

Compare:

• Ten tekst jest jasny. — masculine
• Ta mowa jest jasna. — feminine
• To wyjaśnienie jest jasne. — neuter

It is in the nominative case because it is the subject of the sentence.

The adjective jasna is also in the nominative because it agrees with the subject after być when using an adjective.

So:

• mowa = nominative singular feminine
• jasna = nominative singular feminine

In Polish, every noun has grammatical gender. Mowa is a feminine noun.

A useful beginner clue is that many feminine nouns end in -a, and mowa does too.

Because it is feminine, words describing it must use feminine forms:

• dobra mowa
• jasna mowa
• ta mowa

It can mean both, depending on context.

With physical things, jasny/jasna/jasne can mean:

• bright
• light-colored

With speech, language, explanations, or ideas, it often means:

• clear
• easy to understand

So in Mowa jest jasna, jasna means clear, not literally bright.

Yes.

• mowa usually relates to speech, speaking, or spoken expression
• język usually means language in the sense of a language system, like Polish, English, Spanish

So:

• mowa jest jasna = the speech / way of speaking is clear
• język jest prosty = the language is simple

They can overlap a little in some contexts, but they are not the same word.

Yes, Polish word order is more flexible than English, but the neutral order here is:

Mowa jest jasna.

Other orders are possible, but they change the emphasis:

• Jasna jest mowa. — more literary or emphatic
• Jasna mowa. — compressed, not a full neutral sentence in everyday style

For learners, use Mowa jest jasna as the safest default.

A simple approximate pronunciation is:

MO-va yest YAS-na

A few helpful points:

• w in Polish sounds like English v
• j sounds like English y
• a is usually a clear ah sound
• stress in Polish is usually on the second-to-last syllable:
  • MO-wa
  • jest
  • JAS-na

Polish does not have articles like a or the.

So Mowa jest jasna can mean:

• Speech is clear
• The speech is clear

The exact meaning depends on context.

This is very normal in Polish. You do not need to add any separate word for the.

It is grammatically correct, but by itself it can sound a little textbook-like or context-dependent.

In real life, Polish speakers might more often say things like:

• To jest jasne. = That is clear.
• Ta mowa jest jasna. = This speech is clear.
• Jego sposób mówienia jest jasny. = His way of speaking is clear.

Still, Mowa jest jasna is a perfectly good example for learning grammar.