The output is sorted due to the fact that for each number, a timer is started that prints out the number after waiting a number of milliseconds equal to said number.
Therefore, 1 is printed first after delaying for 1 millisecond, 5 is printed second after 5 milliseconds etc.
They are launched sequentially, but run simultaneously, yes - at least some of them. And they run concurrently but not in parallel - using a single execution context, there is only a single thread, so no parallelism exist.