Słońce świeci wysoko na niebie.

Word by word:

• słońce = sun
• świeci = shines / is shining
• wysoko = high
• na = on / in / at depending on context
• niebie = sky in the locative case

So the sentence literally comes out as something like The sun shines high in the sky.

Świecić is the dictionary form of the verb, meaning to shine.

In the sentence, you need a conjugated form, because Polish verbs change depending on the subject.
Here the subject is słońce (the sun), which is 3rd person singular, so:

• świecić = to shine
• świeci = it shines / is shining

So Słońce świeci means The sun shines or The sun is shining.

It can mean both.

Polish present tense often covers both:

• The sun shines
• The sun is shining

The exact English translation depends on context. In this sentence, either is natural.

Because wysoko is an adverb, and it describes how / where the sun shines.

• wysoki / wysokie = high, tall as an adjective, used with nouns
• wysoko = high as an adverb, used with verbs

Here it modifies the verb świeci:

• świeci wysoko = shines high

You would not use wysokie here, because that would try to describe a noun, not the action.

Niebie is the locative singular form of niebo (sky).

After na, Polish can use different cases depending on meaning:

• na + accusative for movement toward something
• na + locative for location

Here there is no movement. The sun is located high in the sky, so Polish uses na niebie.

Forms:

• niebo = nominative
• niebie = locative

So:

• na niebie = in/on the sky idiomatically in the sky

Because prepositions do not match one-to-one across languages.

In Polish, na niebie is the normal expression for in the sky.
Even though na often means on, here you should learn the whole phrase as a set expression:

• na niebie = in the sky

This is very common in language learning: the preposition that sounds logical in English is not always the one another language uses.

Polish has no articles like a/an or the.

So:

• słońce can mean sun, a sun, or the sun
• context tells you which meaning is intended

In this sentence, it is naturally understood as the sun.

Słońce is neuter.

That is why it has the typical neuter singular ending -e in the nominative form.

This matters because adjectives and some past-tense forms agree with the noun’s gender. For example:

• gorące słońce = hot sun

Here gorące is in the neuter form to match słońce.

A rough guide:

• sł: the ł sounds like English w
• oń: the ń is like ny in canyon, but softer
• ce: here c sounds like ts

So słońce is approximately:

SWOHN-tseh

More carefully, it is closer to swoń-tse, with a soft ń sound.

Also note:

• ó and o are different letters, but here it is plain o
• ł is almost always like English w

A rough pronunciation is:

SHVYEH-chee

Key points:

• ś is a soft sh sound
• w in Polish sounds like English v
• ie here gives a ye-like sound
• ci before a vowel-like ending sounds like a soft ch/ć sound, roughly chee

So świeci is something like sh-vye-chi, but with a softer first and last consonant than in English.

Yes, you can, and it is natural.

Compare:

• Słońce świeci wysoko na niebie = The sun shines high in the sky
• Słońce jest wysoko na niebie = The sun is high in the sky

The first focuses more on the action or visual effect of shining.
The second focuses more on position.

Both are correct, but they are not exactly identical.

Not completely. Polish word order is fairly flexible.

The neutral order here is:

• Słońce świeci wysoko na niebie.

But other orders are possible for emphasis, for example:

• Wysoko na niebie świeci słońce.
• Na niebie słońce świeci wysoko.

These may sound more poetic, marked, or context-dependent.
For everyday neutral usage, the original order is best.

Yes.

Niebo can mean:

• sky
• heaven

Context tells you which is meant.

In na niebie, with the sun shining, it clearly means in the sky.

Usually, yes, but its range is a bit wider than English shine.

It can mean things like:

• to shine
• to give off light
• to be lit
• sometimes even to glow

Examples:

• Słońce świeci. = The sun is shining.
• Lampa świeci. = The lamp is on / shining.

So it is a very useful everyday verb.

It is an adverb.

More specifically, it is related to the adjective wysoki (high / tall), but it functions differently:

• wysoki budynek = a tall building
  
  • adjective describing a noun
• lecieć wysoko = to fly high
  
  • adverb describing a verb

In your sentence:

• świeci wysoko = shines high

So wysoko tells you how high / in what position the action happens.

Yes, grammatically you can.

• Słońce świeci na niebie = The sun is shining in the sky
• Słońce świeci wysoko na niebie = The sun is shining high in the sky

Adding wysoko makes the image more specific. Without it, the sentence is simpler and still correct.