Las bolitas aparecen en el retal.

Las is the feminine plural definite article, meaning the.

• bolita = a little ball / pellet / bobble
• bolitas = little balls / pellets / bobbles
• las bolitas = the little balls

In Spanish, articles are used more often than in English, so las bolitas sounds natural when referring to specific little balls that are known in the context.

Bolitas is the plural of bolita, which is the diminutive form of bola.

• bola = ball
• bolita = little ball

Depending on context, bolitas could mean:

• little balls
• little pellets
• little bobbles
• little lumps

The diminutive -ita / -itas often suggests small size, and sometimes also gives a tone of familiarity or softness.

Because the base word is bola, which is feminine.

• la bola
• la bolita
• las bolitas

When a noun becomes a diminutive, it usually keeps the gender of the original noun.

Because the subject is plural: las bolitas.

The verb aparecer means to appear. It must agree with the subject:

• la bolita aparece = the little ball appears
• las bolitas aparecen = the little balls appear

So aparecen is the third person plural form.

It is the present indicative of aparecer.

Here is the relevant part of the conjugation:

• yo aparezco
• tú apareces
• él/ella aparece
• nosotros aparecemos
• vosotros aparecéis
• ellos/ellas aparecen

In this sentence, aparecen can mean:

• appear
• show up
• are appearing

depending on context.

En usually means in, on, or inside, depending on the context.
El retal means the scrap of cloth / fabric remnant / offcut.

So en el retal means something like:

• in the scrap of fabric
• on the fabric scrap
• in the cloth remnant

The exact English translation depends on what kind of material or situation is being described.

Retal is a noun that usually refers to a piece left over from a larger piece of fabric, so:

• fabric scrap
• cloth remnant
• offcut

It is a real and useful word, especially in sewing, textiles, crafts, or descriptions of materials. In everyday conversation, it may be less common than more general words, but it is perfectly normal in the right context.

Because grammatical gender in Spanish is not determined only by the ending.
Retal is simply a masculine noun:

• el retal
• un retal

Many masculine nouns do not end in -o, and many feminine nouns do not end in -a. The ending can help, but it is not a guarantee.

Yes. That word order is also correct.

Spanish word order is often more flexible than English. Both of these are possible:

• Las bolitas aparecen en el retal.
• En el retal aparecen las bolitas.

The difference is mostly one of emphasis:

• Las bolitas aparecen en el retal focuses first on the little balls
• En el retal aparecen las bolitas focuses first on the fabric scrap / location

Usually yes, but it depends on context.

Aparecer often means:

• to appear
• to show up
• to become visible

So Las bolitas aparecen en el retal suggests that the little balls show up or become visible on/in the fabric scrap.

If the idea were more like there are little balls on the fabric, Spanish might also use other verbs depending on the situation, such as salir or verse in some contexts. But aparecen is perfectly natural for appear.

It can definitely be used for fabric pilling in context. In clothing and textiles, people often use words like:

• bolitas
• pelotillas
• pelusas (depending on what is meant)

So if the sentence is about a piece of cloth, las bolitas could refer to the little balls that form on fabric through wear.

Normally, no. That sounds unnatural in standard Spanish.

Spanish usually needs an article here:

• Las bolitas aparecen en el retal.

Dropping the article is much less common than in English. In very special contexts like labels, headlines, or notes, article omission can happen, but in a normal sentence you should keep las.

It sounds like standard Spanish and works fine in Spain.

A speaker from Spain would understand:

• las bolitas as little balls, little bobbles, or fabric pills depending on context
• retal as a scrap/remnant of cloth or material

So the sentence is natural, especially in a sewing, textile, or fabric-related context.