Zámek je na truhle.

Because na here means on in the sense of location, and with location Czech uses the locative case.

• basic form: truhla = chest, trunk
• locative singular: na truhle = on the chest

So the sentence uses:

• zámek = the lock
• je = is
• na truhle = on the chest

This is a very common pattern in Czech:

• na stole = on the table
• na židli = on the chair
• na truhle = on the chest

Truhle is in the locative singular.

The noun truhla is a feminine noun, and after na when talking about location, it changes into the locative:

• nominative: truhla
• locative: na truhle

A learner often notices that many feminine nouns ending in -a change to -e or -ě in the locative singular.

Yes. Na can mean different things depending on context, but one very common meaning is on.

In this sentence:

• na truhle = on the chest

However, na can also be used in other ways, for example:

• jdu na poštu = I’m going to the post office
• na stole = on the table
• na jaře = in spring

So you should not think of na as matching only one English preposition. Here, because the meaning is already clear, the best translation is on.

Je means is.

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

So:

• já jsem = I am
• ty jsi = you are
• on / ona / ono je = he / she / it is

In Zámek je na truhle, je links the subject and the location:

• Zámek = the lock
• je = is
• na truhle = on the chest

No. Zámek is a famous Czech word because it has more than one meaning.

It can mean:

• lock
• castle
• chateau / manor house

The context tells you which meaning is intended.

In Zámek je na truhle, the natural meaning is lock, because a lock can be on a chest. A castle obviously cannot.

This kind of ambiguity is normal in Czech, just like some English words also have multiple meanings.

Correct. Czech does not have articles like English a and the.

So zámek can mean:

• a lock
• the lock

and truhla / truhle can mean:

• a chest
• the chest

Which one is meant depends on context.

So Zámek je na truhle could be understood as:

• The lock is on the chest
• or A lock is on a chest

But in normal translation, context usually makes one choice more natural.

Yes. Zámek je na truhle is a normal, neutral word order.

A very common Czech pattern is:

subject + je + place

So:

• Kniha je na stole. = The book is on the table.
• Kočka je na střeše. = The cat is on the roof.
• Zámek je na truhle. = The lock is on the chest.

You could change the word order for emphasis, for example:

• Na truhle je zámek. = There is a lock on the chest / The lock is on the chest.

That version puts more focus on the location first.

A simple approximate pronunciation is:

ZAA-mek ye na TROO-hleh

A few helpful points:

• á is a long vowel, so zá- is longer than a short a
• j in Czech sounds like English y in yes
• ch in truhle is not like English ch in chair; it is a rough sound, like the ch in German Bach or Scottish loch
• the stress in Czech is usually on the first syllable of each word:
  • ZÁ-mek
  • je
  • na
  • TRU-hle

Because zámek is the subject of the sentence, so it stays in the nominative case.

In this sentence:

• Zámek = subject, nominative
• je = is
• na truhle = prepositional phrase showing location, with locative

So only truhla changes form, because it comes after na in a location meaning.

Not in this sentence.

Because the sentence uses je and describes a state or location, na truhle means on the chest.

If you wanted to say movement onto the chest, Czech would usually use the accusative after na, for example with a verb of motion:

• Dávám zámek na truhlu. = I am putting the lock onto the chest.

Compare:

• na truhle = on the chest, location
• na truhlu = onto the chest, direction

This location-vs-direction difference is very important in Czech.

It is a real and standard Czech word, but it is not as common in everyday conversation as words like stůl (table) or dveře (door).

Truhla usually means:

• chest
• trunk
• large wooden storage box

It can sound a bit old-fashioned depending on context, because people do not talk about chests every day. But it is completely normal and useful vocabulary, especially in stories, historical contexts, descriptions of furniture, or when talking about storage boxes with lids.