Unassigned Space is mapped and committed virtual memory in use by the process that is not attributable to any particular ...

Unassigned Space is mapped and committed virtual memory in use by the process that is not attributable to any particular image being executed by that process.  Write Copy protection is used when memory is shared for reading but not for writing.  When processes are reading this memory, they can share the same memory, however, when a sharing process wants to have read/write access to this shared memory, a copy of that memory is made for writing to.