It means register with an agency and go wherever you are dispatched to. A real 'Journeyman' in the classic sense. Length of employment at the destination can be random. While there, earn double the hourly pay of the permanent staff nurses there.
A friend of my wife did that for years in a large metropolitan area and never had to go beyond an hour commute. I suppose in the rural states the only work available might be two states over.
And commenting on an earlier topic in the thread - A sub-branch where I worked had the Large Public Agency's internal investigations branch. Just two employees. (I did the research for them in a couple of instances). They had a pet non-specific answer when asked the result of an investigation:
"Oh he moved on to pursue other opportunities elsewhere."