Našli jsme řadu a sedadla před začátkem.

Našli jsme means we found.

It is the Czech past tense of the verb najít (to find). Czech past tense is often formed with:

• a past participle: našli
• plus the auxiliary jsme for we

So:

• našli = found
• jsme = we have / we did, as a past-tense auxiliary here

Together: našli jsme = we found

Also, najít is a perfective verb, so it usually suggests a completed result: we succeeded in finding.

This is because jsme is a clitic in Czech, and clitics usually go in the second position in the sentence or clause.

So in a simple sentence like this:

• Našli jsme řadu a sedadla před začátkem.

the first position is taken by Našli, and jsme comes right after it.

For that reason, Našli jsme sounds natural, while Jsme našli at the beginning of a sentence is generally not the normal neutral order.

You can still move things around, but jsme will usually stay in second position:

• Před začátkem jsme našli řadu a sedadla.
• Řadu a sedadla jsme našli před začátkem.

Because řadu is the accusative singular form of řada.

The noun řada is a feminine noun, and here it is the direct object of the verb found. In Czech, direct objects usually go in the accusative case.

So:

• řada = nominative singular
• řadu = accusative singular

That is why Czech says našli jsme řadu and not našli jsme řada.

Here sedadla is accusative plural of sedadlo (seat).

Sedadlo is a neuter noun. For many neuter inanimate nouns, the nominative plural and accusative plural are the same.

So:

• singular: sedadlo
• plural nominative: sedadla
• plural accusative: sedadla

Because it is also a direct object, accusative is needed, but the form happens to look the same as the nominative plural.

Because Czech does not have articles like the or a/an.

So Czech often leaves definiteness to be understood from context.

For example:

• řadu can mean a row or the row
• sedadla can mean seats or the seats

English has to choose, but Czech usually does not mark this directly. The listener understands it from the situation.

After před here, Czech uses the instrumental case.

The noun is:

• začátek = beginning, start

In the instrumental singular, it becomes:

• začátkem

So:

• před začátkem = before the beginning / before the start

This is a very common pattern:

• před koncertem = before the concert
• před filmem = before the film
• před začátkem = before the beginning

Here it means time.

Although před can also mean in front of in a physical sense, in this sentence před začátkem clearly means before it started or before the beginning.

So the phrase answers when they found the row and seats:

• before the start

not

• in front of the start

It often suggests successful completion.

Because the verb is perfective (najít), našli jsme can carry the idea that the action reached its result:

• we found
• we managed to find
• we succeeded in finding

That does not mean you must always translate it with managed to, but that feeling is often there.

Compare:

• hledali jsme = we were looking for
• našli jsme = we found / we managed to find

Yes. Czech word order is fairly flexible, and changing it often changes emphasis more than basic meaning.

For example:

• Našli jsme řadu a sedadla před začátkem.
  Neutral statement.

• Před začátkem jsme našli řadu a sedadla.
  Emphasizes before the start.

• Řadu a sedadla jsme našli před začátkem.
  Emphasizes the row and the seats.

What stays important is that jsme usually remains in the second position.

It is grammatically correct and understandable, but in real-life Czech a native speaker might choose a more natural phrase depending on context.

If this is about a cinema, theatre, or stadium, many speakers might say:

• Našli jsme svá místa před začátkem. = We found our seats before the start.
• Našli jsme svou řadu a svá sedadla před začátkem. = We found our row and seats before the start.

Why? Because místa (places/seats) is often a very natural word for assigned seating, and adding svá / svou can make it clearer that these were our seats.

So the original sentence is fine, but there are more idiomatic alternatives depending on what exactly you want to stress.