Learn Hardcore Spanish (Spain): Unos cantan en el parque, otros juegan con la pelota. - Some sing in the park, others play with the ball.

It’s masculine plural and is used as a pronoun, not followed by a noun.
The full idea is like “Unos [personas/niños/adultos] cantan…” → Some (people) sing…

In English we usually say “some of them” or just “some”, and Spanish often does the same with unos when the noun is obvious from context.

Why is there no noun after unos or otros? Shouldn’t it be something like unos niños, otros niños?

It could be unos niños, otros niños, but it doesn’t have to be.

Unos and otros can work as pronouns meaning:
- unos → some (people)
- otros → others / other people

So you can say:

Unos cantan en el parque, otros juegan con la pelota.
Some (people) sing in the park, others play with the ball.

The noun (people, children, etc.) is understood from the context, so it’s omitted.

What’s the difference between unos and algunos? Could I say “Algunos cantan en el parque, otros juegan con la pelota”?

Unos and algunos can both mean “some”, but they’re not always interchangeable.

In this contrasting structure, Spanish prefers “unos … otros …”
- Unos cantan en el parque, otros juegan con la pelota. ✅
- Algunos cantan en el parque, otros juegan con la pelota. ❌ (grammatically possible, but sounds off to native ears)
The fixed, natural pattern is:
- Unos … otros … → Some … others …
Outside of that pattern, both are often okay:
- Unos amigos vinieron ayer.
- Algunos amigos vinieron ayer.
  Meaning is basically the same: Some friends came yesterday.

So for this specific sentence, keep unos … otros …, not algunos … otros ….

Why is otros used and not something like los otros? Isn’t it talking about “the others”?

Otros alone already means “others / the others” here.

Unos introduces a first group: some (people).
Otros automatically refers to the rest / the remaining ones, so adding los is usually unnecessary.

You could sometimes say “unos … los otros …”, but in this kind of simple “some … others …” contrast, native speakers just say:

Unos cantan…, otros juegan…

That’s the most natural pattern.

Why is it cantan and juegan, not canta and juega?

Because both unos and otros are plural.

Unos → they (some of them)
- ellos cantan → cantan
Otros → they (the others)
- ellos juegan → juegan

So the verbs must agree in number:

Unos cantan… (Some [plural] sing…)
Otros juegan… (Others [plural] play…)

Using singular (canta, juega) would be ungrammatical in this sentence.

Does “Unos cantan…” mean “Some sing” or “Some are singing”? Where is the Spanish continuous form?

It can mean both:

Some sing in the park (habitually, generally)
Some are singing in the park (right now, in this situation)

Spanish simple present (cantan, juegan) often covers what English expresses with both:

They sing
They are singing

If you really want to emphasize that it’s happening right now, you can use the progressive:

Unos están cantando en el parque, otros están jugando con la pelota.

But in normal speech, cantan / juegan is usually enough; context gives the time sense.

Why is it en el parque and not al parque?

Because the meaning is “in the park”, not “to the park”.

en el parque → in the park (location, where they are)
al parque (a + el parque) → to the park (direction, where they’re going)

In this sentence, the action happens inside the park:

Unos cantan en el parque…
Some (people) sing in the park…

So en, not a, is correct.

Why is it con la pelota and not “juegan la pelota” or “juegan a la pelota”?

With pelota (ball), Spanish normally uses jugar con + thing:

jugar con la pelota → to play with the ball

Some patterns to remember:

jugar a + game/sport
- jugar al fútbol, jugar al tenis, jugar a las cartas
jugar con + object/toy
- jugar con la pelota, jugar con coches, jugar con muñecas

So:

Otros juegan con la pelota. ✅
Otros juegan la pelota. ❌ (not natural)
Otros juegan a la pelota. ✅ (exists, but usually means a specific game called la pelota; more regional/sport-specific)

In everyday European Spanish, “juegan con la pelota” for kids just playing with a ball is the normal choice.

Why is it la pelota and not una pelota? Would that change the meaning?

Yes, it slightly changes the nuance.

la pelota → the ball (a specific, known ball in the situation)
una pelota → a ball (just any ball, non-specific)

So:

Otros juegan con la pelota.
→ Suggests there is one particular ball everyone knows about (maybe the one in the scene).
Otros juegan con una pelota.
→ Introduces a ball that hasn’t been specified before; it’s just some ball.

Both are grammatically correct; the sentence with la sounds like part of a scene already being described.

What’s the difference between pelota and balón in Spain? Both mean “ball,” right?

Both refer to balls, but they’re used a bit differently in Spain:

pelota
- Very general: any ball, especially smaller / lighter ones (tennis ball, rubber ball, kids’ balls).
- Also used in some specific sports (e.g., pelota vasca).
balón
- Usually bigger, heavier balls used in sports: fútbol, baloncesto, balonmano, etc.

In casual talk about kids in a park:

jugar con la pelota is more natural and generic.
jugar con el balón would make people think more of a football/basketball-type ball.

Is the comma between the two parts correct, or should there be y (and)?

The comma is correct and natural.

Unos cantan en el parque, otros juegan con la pelota.

The comma separates two parallel clauses that contrast:

Unos … → first group
otros … → second group

You could add y, but it feels heavier and is less usual here:

Unos cantan en el parque y otros juegan con la pelota. (also correct)

In writing, the comma without “y” is very common and stylistically neat in this “some … others …” structure.

Do unos and otros have to match gender? What if we’re talking about girls?

Yes, they must agree in gender and number with the group they refer to.

For a mixed group or an all-male group (default masculine):
- Unos cantan…, otros juegan…
For an all-female group:
- Unas cantan en el parque, otras juegan con la pelota.

So:

unos / otros → masculine plural
unas / otras → feminine plural

Spanish grammar requires this agreement, even if English just uses “some” / “others” for all cases.