I agree, Mav, that this is a poor translation. I have no doubt this refers to what we USns call a vacant lot, which is a bare and unused tract of ground in the midst of inhabited tracts which are in use. It is usually a piece of ground which has somehow never been built on whilst its neighbors have been put to use, or in some cases one which did have some improvement (technical term for "building") which has burned down and disappeared or torn down, and never replaced.