It means one can spring-clean to a certain extent, and throw out accumulated debris, and even some stuff that one makes up one's mind to do without. Some stuff that is useful here is useless there, and can be kept aside, or discarded.
If only death were also always like this, with a certain date and time specified! One could wind up one's affairs neatly, pass on the baton, and go gently into that good night. Packing, of course, wouldn't be a problem at all :)..but one's belongings could be neatly disposed of.
But when push came to shove, would we be any less scared of that permanent leap into the unknown, with prior knowledge of when we are to die, as when death arrives upon us unexpectedly? I wonder.