what is bad in my code i don't understand

[thick schooner]

There's no world.players

And world.addObjectives and world.setObjective

Also, wrap inside system.runTimeout

[dusk pawn]

It seems you didn't read the official documentation.

[thick schooner]

import { world, system } from "@minecraft/server"

system.runTimeout(() => {
  const score = world.scoreboard
  const obj =  score.addObjective("Hola", "Hola") 
  score.setObjectiveAtDisplaySlot("sidebar", { objective: obj })

  world.getAllPlayers().forEach(player => {
    player.scoreboard.setScore(obj, 0)
  })
})

//...

[dusk pawn]

Is the spread operator really necessary, ie world.getAllPlayers() returns an Array of Players.

[thick schooner]

I don't think so

But I'm just trying to be safe so I don't get an error

[dusk pawn]

Oh, okay.

[thick schooner]

Done