If you have "Shaun" currently set as the name, and you'd change it to Peace; then at that point "Shaun" is being held for you.
In 28 days, you will be able to change your name again; from there and then you will get a couple of weeks (longer if you had "Shaun" for a long time) to change your name back to "Shaun". On the other hand, if you change your name from "Peace" to "dfjsmlkqfjm" for example, "Shaun" will no longer be held for you, and it'll become available as soon as you accept the second name change.
At that point, "Peace" will be held for you for 28 days + a little more than a week in case you'd like to change it back to that, (it's only a bit more than a week since you didn't have it for that long).
I hope that's clear, if not I'll try to rephrase myself.