Bawełna, wełna i len są na stole.

Because the sentence has a compound subject: bawełna, wełna i len = cotton, wool, and flax/linen.
Each noun is singular by itself, but together they form a plural subject, so Polish uses the plural verb są = are.

• bawełna jest = cotton is
• wełna jest = wool is
• len jest = flax is
• bawełna, wełna i len są = cotton, wool, and flax are

Because after na with the meaning on in a static location, Polish uses the locative case.

So:

• stół = table (dictionary form, nominative)
• na stole = on the table (locative)

Compare:

• na stole = on the table, already there
• na stół = onto the table, movement toward it

In your sentence, the things are already on the table, so na stole is correct.

They are in the nominative case, because they are the subject of the sentence.

• bawełna — nominative singular
• wełna — nominative singular
• len — nominative singular

The noun stół changes because it comes after the preposition na in a location phrase, so it becomes stole.

Because stole is the locative singular form of stół.

Some common forms of stół are:

• stół — nominative
• stołu — genitive
• stołowi — dative
• stół — accusative
• stołem — instrumental
• stole — locative

Since na here expresses location, Polish requires the locative: na stole.

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

So Bawełna, wełna i len są na stole can mean:

• cotton, wool, and flax are on the table
• the cotton, the wool, and the flax are on the table

The exact meaning depends on context. Polish usually leaves that unstated unless something else makes it clear.

Yes, i usually means and.

In this sentence:

• bawełna, wełna i len = cotton, wool, and flax

It is the normal coordinating conjunction for joining words or phrases.

Polish also has oraz and a in some contexts, but i is the basic everyday word for and.

In Polish, when listing three or more items, commas separate the earlier items, just like in English.

So:

• Bawełna, wełna i len = cotton, wool, and flax

There is no comma directly before i here in standard punctuation. The comma only separates the first two listed items.

Their grammatical genders are:

• bawełna — feminine
• wełna — feminine
• len — masculine

This matters for agreement in some structures, especially adjectives and past tense forms.

For example:

• biała wełna = white wool
• biała bawełna = white cotton
• biały len = white flax/linen

Not exactly. Len literally means flax, the plant. By extension, it can also refer to linen as a material, depending on context.

So in a materials list like this sentence, len is often best understood as flax or linen material.

A learner should just remember that len is the Polish word connected with the material linen.

A rough English-friendly guide is:

• bawełna ≈ ba-VEW-na
• wełna ≈ VEW-na
• i ≈ ee
• len ≈ len
• są ≈ nasal saw̃ / soh̃
• na ≈ nah
• stole ≈ STO-leh

A few useful notes:

• Polish w sounds like English v
• ł sounds like English w
• ą is a nasal vowel, not a plain a

So wełna can feel surprising: it sounds roughly like vew-na, not like it starts with an English w.

Yes. Polish word order is more flexible than English because case endings show grammatical relationships.

The neutral order here is:

• Bawełna, wełna i len są na stole.

But you could also say:

• Na stole są bawełna, wełna i len.

That version puts more focus on the location: On the table are cotton, wool, and flax.

Both are grammatical, but the original sentence is a straightforward neutral statement.

Because są is simply the 3rd person plural present tense of być (to be).

The present tense of być is:

• jestem — I am
• jesteś — you are
• jest — he/she/it is
• jesteśmy — we are
• jesteście — you are
• są — they are

Since the subject is plural, Polish uses są.

Yes. In this sentence, they are most naturally understood as materials/substances: cotton, wool, and flax/linen.

Polish often uses singular nouns for materials, just as English does:

• Bawełna jest miękka. = Cotton is soft.
• Wełna jest ciepła. = Wool is warm.

In your sentence, the meaning is probably something like the cotton, wool, and linen are on the table—for example, pieces of fabric or samples of material. Context tells us exactly what physical items are meant.