JS OOP – class method calling another class from function

I was curious about JS Design Patterns and decided to try this website,
but on the Command Pattern section I got super confused. You can see the explanation in the link but for this post’s sake I have provided a code snippet below.

class OrderManager {
    constructor() {
        this.orders = [];
    }

    execute(command, ...args) {
        return command.execute2(this.orders, ...args);
    }
}
  
class Command {
    constructor(executee) {
        this.execute2 = executee;
    }
}

function PlaceOrderCommand(order, id) {
    return new Command(orders => {
        orders.push(id);
        console.log(`You have successfully ordered ${order} (${id})`);
    });
}

const manager = new OrderManager();

manager.execute(new PlaceOrderCommand("Pad Thai", "1234"));

I am super confused, I thought I was good at JS but apparently I am not..

The questions in line are:

1. How can you call the manager.execute with only one argument, when in the definition there are two?!

2. Why call the function with new keyword like new PlaceOrderCommand(“Pad Thai”, “1234”)

3. How does execute2 call the arrow function when it is just assigned in the constructor?!

all these things are super confusing and seem like magic to me..