Znak szlaku jest na drzewie.

Word by word:

• znak = sign, mark, symbol
• szlaku = of the trail / route / path
• jest = is
• na = on
• drzewie = tree, in the form needed after na for location

So the whole sentence means something like The trail sign is on the tree.

Because szlaku is the genitive singular form of szlak.

In znak szlaku, Polish is expressing a relationship like:

• sign of the trail
• trail sign
• trail marker

English often uses a noun directly before another noun, as in trail sign. Polish usually does this with the second noun in the genitive:

• znak szlaku = sign of the trail
• kolor ściany = color of the wall
• nazwa miasta = name of the city

So szlak changes to szlaku because it depends on znak.

Because after na, when you are talking about location and not movement, Polish uses the locative case.

Here the meaning is on the tree as a location, so:

• na drzewie = on the tree

Compare:

• Znak jest na drzewie. = The sign is on the tree.
  
  • location → locative
• Wieszam znak na drzewo. = I hang the sign onto the tree.
  
  • movement toward a target → often accusative

So drzewie is the locative singular form of drzewo.

It is the locative singular of drzewo.

The basic form is:

• drzewo = tree

After certain prepositions used for location, such as na, w, o, Polish often uses the locative:

• na drzewie = on the tree
• w domu = in the house
• o szkole = about the school

So in this sentence:

• na
  • location
• therefore drzewie is in the locative

That is a very common question.

Polish often omits to be in sentences like:

• To jest dobre → often just To dobre is not natural; actually for demonstrative predication you usually keep to jest; but in adjective predicates like On jest zmęczony colloquially On zmęczony is not standard either.

  More importantly, in normal standard Polish, jest is often still used, especially in sentences of existence or location:

• Książka jest na stole. = The book is on the table.
• Znak jest na drzewie. = The sign is on the tree.

So in this sentence, jest is natural and expected.

Yes. Polish word order is more flexible than English word order.

The neutral version is:

• Znak szlaku jest na drzewie.

But you could also say:

• Na drzewie jest znak szlaku.

Both are grammatical. The difference is mainly emphasis or information structure:

• Znak szlaku jest na drzewie.
  starts with the sign; good if you are talking about the sign
• Na drzewie jest znak szlaku.
  starts with the location; good if you are pointing out what is on the tree

English has less flexibility here.

Because the sign is understood as being attached to the outside surface of the tree.

• na = on
• w = in

So:

• na drzewie = on the tree
• w drzewie = in the tree

If something is painted on the bark, nailed to the trunk, or attached to the outside, na drzewie is the natural choice.

Yes, it usually suggests a trail marker or route sign, especially in hiking or marked-path contexts.

• szlak can mean trail, route, marked path
• znak szlaku is the sign/mark that shows that trail

In practice, it might be a painted blaze on a tree, a symbol, or another trail marker.

Because Polish does not have articles like English a/an/the.

So znak can mean:

• a sign
• the sign

And drzewie can mean:

• on a tree
• on the tree

Which meaning is intended depends on context.

That is very normal in Polish, and learners have to get used to using context instead of articles.

The hardest parts for English speakers are usually the consonant clusters.

A rough guide:

• znak ≈ znahk
• szlaku ≈ shLAH-koo
• jest ≈ yest
• na ≈ nah
• drzewie ≈ DZHVEH-vye

A few helpful points:

• sz sounds like English sh
• rz here sounds like zh or ż
• ie often sounds like ye after a consonant

So the whole sentence is roughly:

• ZNAHK shLAH-koo yest nah DZHVEH-vye

This is only an approximation, but it helps.

It may feel irregular at first, but it is a normal locative form of drzewo.

Basic pattern:

• drzewo = nominative singular
• drzewie = locative singular

Many neuter nouns in -o change in oblique cases, so learners should memorize the case forms rather than expect the stem to stay exactly the same in every situation.

So the important thing to remember is simply:

• na drzewie = on the tree

Yes, grammatically that is exactly what it means.

But in natural English, depending on context, you would usually say:

• trail sign
• trail marker
• route marker

So:

• literal structure: sign of the trail
• natural English meaning: trail sign / trail marker