Pas je ještě platný.

• Pas = passport. It is the subject of the sentence.
• je = is, the 3rd person singular present form of být (to be).
• ještě = still in this sentence.
• platný = valid.

So the structure is basically:

passport + is + still + valid

This is a very normal Czech sentence pattern:
subject + form of být + adverb + adjective

Je is the present-tense form of být (to be) for he/she/it.

Since pas is a singular noun, Czech uses singular je:

• Pas je platný. = The passport is valid.

Compare:

• Pasy jsou platné. = The passports are valid.

So je agrees with the singular subject pas.

Because adjectives in Czech must agree with the noun they describe.

Here, pas is:

• masculine
• inanimate
• singular
• in the nominative case

So the adjective also takes the matching form:

• platný

A few comparison examples:

• pas je platný → masculine inanimate singular
• karta je platná → feminine singular
• vízum je platné → neuter singular
• pasy jsou platné → plural

So platný is not just the dictionary form by accident; it matches pas.

Here, ještě means still.

So:

• Pas je ještě platný. = The passport is still valid.

That is the most natural meaning in this sentence.

Czech ještě can sometimes correspond to English yet, but not in this exact structure. For example:

• Ještě ne. = Not yet.

So:

• ještě platný = still valid
• ještě ne = not yet

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

So pas can mean:

• a passport
• the passport

The exact meaning depends on context.

In this sentence, English will often use the:

• The passport is still valid.

But Czech simply says:

• Pas je ještě platný.

This is completely normal.

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

You can tell from the sentence structure:

• Pas is the thing being described
• the sentence says something about it: that it is still valid

So nominative is expected.

Dictionary form:

• pas = nominative singular

Other cases would look different, for example:

• bez pasu = without a passport / without the passport
  here pasu is genitive

But in Pas je ještě platný, nominative is the correct case.

Yes. Czech word order is more flexible than English, although different orders can change the emphasis.

Neutral order:

• Pas je ještě platný.

You could also hear:

• Pas je platný ještě.
  This is less neutral and sounds more marked.
• Ještě je pas platný.
  This puts more focus on still.
• Platný je ještě pas.
  Very marked; used only in specific contexts.

For learners, the safest default is:

Pas je ještě platný.

That is the most straightforward and natural version.

No. Platný is a common adjective meaning valid, in force, or effective, depending on context.

Examples:

• jízdenka je platná = the ticket is valid
• občanský průkaz je platný = the ID card is valid
• zákon je platný = the law is valid / in force

So platný is a general word, not something used only with passports.

A very common way is:

• Pas už není platný.

Breakdown:

• už = already / anymore / now
• není = is not

So this literally feels like:

• The passport is already not valid but in natural English:
• The passport is no longer valid.
• The passport isn’t valid anymore.

You can also say:

• Pas není platný. = The passport is not valid.

Adding už gives the idea of anymore / no longer.

A rough pronunciation guide:

• Pas ≈ pahs
• je ≈ yeh
• ještě ≈ YESH-tyeh or YESH-tye
• platný ≈ PLAHT-nee

A few useful sound notes:

• j in Czech is like English y in yes
• š sounds like English sh
• ě often makes the preceding consonant sound softer; here learners often approximate ještě as yeshtye
• ý is a long ee sound

So a rough full version is:

pahs yeh yesh-tyeh plaht-nee

Because the correct adjective here is platný, and it has to match the noun.

For a masculine inanimate singular noun like pas, the correct nominative form is:

• platný

The form platen is not the correct standard adjective form here.

This is an important Czech pattern: you usually learn adjectives in the masculine singular nominative form, often ending in -ý or -í, and then they change according to gender, number, and case.

So:

• dictionary/basic form: platný
• in this sentence: also platný, because it matches pas

Yes, but that is not a full sentence by itself in the same way.

• Pas je ještě platný. = full sentence = The passport is still valid.
• ještě platný pas = noun phrase = a still-valid passport / a passport that is still valid

So:

• Pas je ještě platný. → statement
• Ještě platný pas leží na stole. → The still-valid passport is lying on the table.

In other words, platný can be:

• a predicate adjective after je
• or a normal attributive adjective before a noun