Unlimited Single Permit - After Obtaining : Labour Market

On the website, it is stated that with an unlimited single permit, we can work for any employer and in any job. What exactly does this mean?

For example, can we work as a painter in an art studio or as a waiter in a café? In this case, is there a minimum salary requirement?

And can we also do part-time jobs? For example, does a part-time job fall under this as well?