Oznakowanie jest co prawda jasne, ale jeden znak szlaku jest zepsuty.

This is a very common Polish pattern meaning something like:

• it is true that ..., but ...
• admittedly ..., but ...
• granted ..., but ...

So:

• Oznakowanie jest co prawda jasne, ale...
  = The signage is admittedly clear, but...

It introduces a concession: the speaker accepts one positive point, then contrasts it with a problem.

A close equivalent structure is:

• Wprawdzie ... ale ...

Both are common, though co prawda ... ale ... often feels especially natural in everyday speech.

Oznakowanie means signage, marking, or the system of signs/markers in a place.

In this sentence, it refers to the overall trail marking system, not just one individual sign.

So there is a contrast between:

• oznakowanie = the signage/marking as a whole
• jeden znak szlaku = one specific trail sign

This is why the sentence can say that the overall signage is clear, but one particular sign is broken.

Yes, jasny / jasna / jasne can mean bright or light-colored, but it also often means:

• clear
• easy to understand
• easy to follow

In this sentence, jasne means clear.

So:

• Oznakowanie jest jasne
  = The signage is clear

Because oznakowanie is a neuter noun, the adjective also takes the neuter form:

• jasny (masculine)
• jasna (feminine)
• jasne (neuter)

Because there are really two separate statements joined together:

1. Oznakowanie jest co prawda jasne
2. ale jeden znak szlaku jest zepsuty

In English, we also usually repeat is:

• The signage is clear, but one trail sign is broken.

Polish could sometimes omit repeated elements in other contexts, but here repeating jest is the most natural and normal structure.

Jeden literally means one, but in many sentences it can also emphasize a single one particular item.

So:

• znak szlaku = a trail sign / trail marker
• jeden znak szlaku = one trail sign / one of the trail signs

Using jeden helps highlight that the problem concerns only one sign, not the whole marking system.

That fits the contrast in the sentence very well:

• the signage overall is clear,
• but one sign is broken.

Because szlaku is the genitive singular form of szlak.

Base form:

• szlak = trail, route

Here, Polish uses a noun + genitive structure:

• znak szlaku
  literally: sign of the trail naturally: trail sign or trail marker

This is very common in Polish. English often uses one noun directly before another (trail sign), but Polish often expresses this relationship with the genitive case.

So:

• znak = sign
• szlaku = of the trail

Zepsuty means:

• broken
• damaged
• out of order
• not working properly

It comes from the verb zepsuć = to break / to spoil / to damage.

The ending -y is there because zepsuty agrees with znak, which is a masculine noun:

• znak — masculine
• therefore: zepsuty

Compare:

• zepsuty znak = broken sign
• zepsuta lampa = broken lamp
• zepsute urządzenie = broken device

So the adjective changes according to gender and number.

Not quite.

• oznakowanie = the overall marking/signage system
• znak szlaku = one individual sign/marker on the trail

Think of it like this:

• oznakowanie = all the signs and markers together
• znak = one sign

That distinction is important in the sentence. The speaker is saying:

• overall, the signage is clear,
• but one specific marker is broken.

Yes, Polish word order is fairly flexible, though some versions sound more natural than others.

The original sentence is very natural:

• Oznakowanie jest co prawda jasne, ale jeden znak szlaku jest zepsuty.

You might also see variations like:

• Co prawda oznakowanie jest jasne, ale jeden znak szlaku jest zepsuty.
• Oznakowanie jest jasne, ale jeden znak szlaku jest zepsuty.

These all work, but the original wording gives a nice balanced contrast.

Moving co prawda earlier often makes the concessive structure even more obvious.

It is neutral and very common. You can use it in:

• everyday speech
• writing
• descriptions
• more formal contexts

It does not sound slangy. It is a standard expression.

A near equivalent, slightly more bookish or formal in some contexts, is:

• wprawdzie

For example:

• Wprawdzie oznakowanie jest jasne, ale jeden znak szlaku jest zepsuty.

This means essentially the same thing.

A native speaker would probably understand it as:

• The trail markings are generally clear, but one of the trail signs is broken.

So the sentence does two things at once:

1. it gives some positive information about the overall situation,
2. then it points out a specific flaw.

That makes it a very natural sentence for describing directions, hiking routes, public signage, or route conditions.