Těsnění je rozbité.

Těsnění is neuter.

A useful clue is the ending -í / -ní, which is very common in Czech neuter nouns, especially nouns formed from verbs.
So in this sentence:

• těsnění = neuter singular noun
• rozbité = adjective agreeing with a neuter singular noun

That is why you see rozbité, not rozbitý or rozbitá.

Because Czech adjectives must agree with the noun they describe.

Here, těsnění is:

• neuter
• singular
• nominative

So the adjective must also be neuter singular nominative:

• masculine: rozbitý
• feminine: rozbitá
• neuter: rozbité

So:

• Těsnění je rozbité. = neuter noun + neuter adjective

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

So the sentence is literally structured like:

• Těsnění = the seal / gasket
• je = is
• rozbité = broken

Unlike Russian or some other Slavic languages, Czech normally does use the present tense of to be in sentences like this.

So you need:

• Těsnění je rozbité.

not just:

• Těsnění rozbité. ❌

In standard Czech, no—not in a normal full sentence like this.

Czech usually requires the present-tense form of být:

• On je doma. = He is at home.
• Auto je nové. = The car is new.
• Těsnění je rozbité. = The seal is broken.

You might sometimes see omissions in headlines, notes, or very informal speech, but for regular grammar, keep je.

In practice, learners usually treat rozbitý / rozbitá / rozbité as an adjective meaning broken.

Historically and grammatically, it is related to a passive participle from the verb rozbít = to break. But in a sentence like this, it functions just like an adjective:

• Dům je starý. = The house is old.
• Telefon je rozbitý. = The phone is broken.

So the easiest way to think about it is:

• rozbitý = broken
• it changes endings like an adjective

It can mean both, depending on context.

In Czech, rozbitý is often used more broadly than English broken. It can mean:

• physically damaged
• cracked
• smashed
• not functioning properly

For example:

• Telefon je rozbitý. = The phone is broken.
• Zámek je rozbitý. = The lock is broken.
• Těsnění je rozbité. = The seal/gasket is broken/damaged.

So if the object no longer works properly because it is damaged, rozbitý is very natural.

Because Czech has no articles like English a / an / the.

So:

• Těsnění je rozbité.

can mean:

• The seal is broken
• A seal is broken
• The gasket is broken

The exact meaning depends on the context.

Czech speakers understand definiteness from the situation, not from a separate article word.

It is in the nominative singular.

Why nominative? Because těsnění is the subject of the sentence:

• Těsnění = subject
• je rozbité = predicate

The adjective rozbité also appears in the nominative here because it agrees with the subject in this type of sentence.

So the basic pattern is:

• [subject in nominative] + je + [adjective agreeing with subject]

Yes. Czech word order is fairly flexible, but the most neutral version is:

• Těsnění je rozbité.

You could also hear:

• Rozbité je těsnění.
• Je rozbité těsnění.

But these have different emphasis or sound less neutral depending on context.

For a learner, the safest default is:

• subject + je + adjective

So stick with:

• Těsnění je rozbité.

Roughly, it sounds something like tyes-nye-nyee, but that English approximation is imperfect.

A few important points:

• tě: the ě softens the preceding consonant, so tě sounds roughly like tye
• sně: the ň sound is like Spanish ñ or the ny in canyon
• final -í is a long vowel

So a rough learner-friendly pronunciation is:

• TYEHS-nyeh-nyee

But the real Czech sounds are softer and more connected than this English-style approximation.

It is a neuter noun, and it is also the kind of noun often formed from a verb.

Czech has many nouns ending in -ní / -ení / -ání, often connected with actions, processes, or results of actions. For example, nouns of this type can refer to things like:

• sealing
• insulation
• packaging
• heating

In real usage, těsnění can refer to:

• sealing
• a seal
• a gasket

The exact meaning depends on context, but grammatically it behaves here as a singular neuter noun.

The adjective would change to match the noun.

For example:

• masculine: Motor je rozbitý. = The engine is broken.
• feminine: Pračka je rozbitá. = The washing machine is broken.
• neuter: Těsnění je rozbité. = The seal/gasket is broken.

This is one of the most important patterns in Czech:

• -ý for masculine
• -á for feminine
• -é for neuter

So rozbité is telling you something important about těsnění: it is neuter.