Číselná kombinace je správné řešení a zámek se otevře.

Because kombinace is a feminine noun in Czech, and adjectives must agree with the noun in gender, number, and case.

• kombinace = feminine singular
• so the adjective must also be feminine singular: číselná

Compare:

• číselná kombinace = a numerical combination
• číselný kód = a numerical code (kód is masculine)
• číselné řešení = a numerical solution (řešení is neuter)

So číselná matches kombinace.

For the same reason: adjective agreement.

• řešení is a neuter noun
• therefore správný becomes správné in neuter singular nominative

So:

• správné řešení = the correct solution

A few matching examples:

• správný zámek = the correct lock/keyed lock setting? (masculine)
• správná odpověď = the correct answer (feminine)
• správné řešení = the correct solution (neuter)

Je is the 3rd person singular form of být (to be), so it means is.

The structure is:

• Číselná kombinace = the numerical combination
• je = is
• správné řešení = the correct solution

So literally:

• The numerical combination is the correct solution.

Czech often uses je exactly where English uses is in this kind of sentence.

Here řešení is in the nominative singular.

In a sentence with být (to be), Czech often uses the nominative for both sides of an identifying statement:

• Číselná kombinace je správné řešení.

Both kombinace and řešení are nominative here.

English learners sometimes expect another case, but nominative is normal in this kind of equation-like sentence: X is Y.

Yes, zámek has two common meanings:

• lock
• castle/chateau

In this sentence, it clearly means lock, because of the context:

• zámek se otevře = the lock will open / the lock opens

A castle obviously would not be opening because of a number combination, so context removes the ambiguity.

This is a very common Czech word with two meanings, and learners often notice it early.

Here se is part of the verb phrase and helps make the meaning open in an intransitive/reflexive sense:

• otevřít = to open something
• otevřít se / otevře se = to open

So compare:

• Otevřu zámek. = I will open the lock.
• Zámek se otevře. = The lock will open.

In English, this is the difference between:

• Someone opens the lock and
• The lock opens

So se does not mean itself in a strong literal sense here; it is just part of the normal Czech way of saying that something opens.

Great question. In Czech, perfective verbs use present-tense forms to express future meaning.

• otevřít is a perfective verb
• its form otevře literally looks present
• but it usually means will open

So:

• zámek se otevře = the lock will open

This is normal Czech grammar.

Compare:

• otevírá (imperfective) = is opening / opens habitually
• otevře (perfective) = will open / opens once to completion

So the sentence suggests a completed result: once the correct combination is entered, the lock opens.

Yes. Zámek se otevře is the natural choice when you mean the lock will open.

Without se, otevře normally expects an object or a subject that actively opens something:

• Petr otevře dveře. = Petr will open the door.

If you say:

• zámek otevře it sounds incomplete, like the lock will open something, which is not what you want.

So for the lock opens / will open, Czech uses:

• zámek se otevře

Yes, a here simply means and.

It connects two clauses:

1. Číselná kombinace je správné řešení
2. zámek se otevře

So the full sentence means:

• The numerical combination is the correct solution, and the lock will open.

Depending on context, English might also phrase this more naturally as:

• The number combination is the correct solution, and the lock will open.
• The numeric combination is the right solution, and the lock will open.

Yes, depending on context, that can sound more natural in English.

The Czech word řešení most literally means:

• solution

But in some situations English would prefer:

• answer
• correct answer

For example, in a puzzle or code-breaking context, English speakers might say:

• The number combination is the correct answer.

So řešení is literally solution, but a smoother English translation may vary by context.

Czech word order is fairly flexible, but changing it changes the emphasis.

The neutral version is:

• Číselná kombinace je správné řešení a zámek se otevře.

You could also see variations like:

• Správné řešení je číselná kombinace.
  • emphasizes správné řešení
• A zámek se otevře.
  • a can also help continue a narrative

However, the original order sounds natural and straightforward.

Czech uses word order more for focus and information structure than English does, because grammatical roles are often shown by endings rather than position alone.

Because Czech has no articles.

So Czech does not distinguish directly between:

• a numerical combination
• the numerical combination

using separate words like a/an/the.

Instead, Czech relies on:

• context
• word order
• stress/emphasis
• the broader situation

So Číselná kombinace could mean:

• a numerical combination
• the numerical combination

and zámek could mean:

• a lock
• the lock

In this sentence, context makes it sound definite in English:

• The numerical combination is the correct solution and the lock will open.

Yes, it is understandable and natural, especially in contexts involving:

• locks
• safes
• codes
• puzzles

It means something like:

• number combination
• numerical combination

In everyday English, combination is often the most natural translation in the context of locks:

• the correct combination
• the lock combination

In Czech, speakers might also use related words depending on context, such as:

• kód = code
• číselný kód = numerical code

But číselná kombinace is perfectly fine here.

Because of the perfective aspect of otevřít.

Czech verbs often come in aspect pairs:

• otevírat = imperfective
• otevřít = perfective

Perfective verbs focus on:

• completion
• a single whole event
• the result

So zámek se otevře suggests:

• the lock will open once
• the opening will happen successfully
• the event reaches its endpoint

If you wanted repeated or ongoing opening, Czech would more likely use an imperfective form, depending on the context.

This aspect distinction is one of the most important things for English speakers learning Czech.